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Quantitative Examination of Supra-Arcade Downflows in Eruptive Solar Flares
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David E McKenzie Submitted: 2009-05-19 15:43
Downward motions above post-coronal mass ejection flare arcades are an unanticipated discovery of the Yohkoh mission, and have subsequently been detected with TRACE, SOHO/LASCO, SOHO/SUMER, and Hinode/XRT. These supra-arcade downflows are interpreted as outflows from magnetic reconnection, consistent with a three-dimensional generalization of the standard reconnection model of solar flares. We present results from our observational analyses of downflows, which include a semiautomated scheme for detection and measurement of speeds, sizes, and--for the first time--estimates of the magnetic flux associated with each shrinking flux tube. Though model dependent, these findings provide an empirical estimate of the magnetic flux participating in individual episodes of patchy magnetic ... [READ MORE]
Authors: D. E. McKenzie and Sabrina L. Savage
Projects: TRACE,Yohkoh-SXT
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Publication Status: Accepted for publication in ApJ
Last Modified: 2009-05-20 09:24
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Publication Status: ApJL (published)
Last Modified: 2011-06-23 09:22
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Publication Status: ApJ 736, 102-121, (2011)
Last Modified: 2011-08-08 15:37
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Publication Status: published in Solar Physics 07/2011
Last Modified: 2011-07-26 09:23
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Publication Status: Accepted
Last Modified: 2011-11-18 09:30
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Publication Status: accepted for publication in The Astrophysical Journal Letters
Last Modified: 2011-12-20 07:51
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Publication Status: ApJ Letters, accepted
Last Modified: 2011-12-19 09:06
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Publication Status: ApJ Letters, Vol. 745, January 2012, in press
Last Modified: 2012-01-04 12:14
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Publication Status: A&A (accepted)
Last Modified: 2012-01-24 11:24
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Publication Status: PASJ (accepted)
Last Modified: 2011-07-12 11:14
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Publication Status: Published in Astronomy & Astrophysics (2008), v.481, L65-L68
Last Modified: 2009-05-20 09:24
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Rapid Changes of Photospheric Magnetic Field After Tether-cutting Reconnection and Magnetic Implosion
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Chang Liu Submitted: 2011-12-13 14:20
This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.
Authors: Chang Liu, Na Deng, Rui Liu, Jeongwoo Lee, Thomas Wiegelmann, Ju Jing, Yan Xu, Shuo Wang, and Haimin Wang
Projects: Hinode/SOT,RHESSI,SDO-AIA,SDO-HMI
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Publication Status: ApJ Letters, accepted
Last Modified: 2011-12-13 14:37
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Publication Status: Published in Annales Geophysicae (Special Issue: SOHO 20 Solar Conference)
Last Modified: 2011-10-24 12:56
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Atomic data for the X-ray lines of Fe VIII & Fe IX
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Brendan O'Dwyer Submitted: 2011-10-06 03:57
This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.
Authors: O'Dwyer, B., Del Zanna, G., Badnell, N. R., Mason, H. E., Storey, P. J.
Projects: SDO-AIA
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Publication Status: Accepted for publication in Astronomy and Astrophysics
Last Modified: 2011-10-06 11:40
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Publication Status: ApJ, in press
Last Modified: 2011-06-14 19:51
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Publication Status: Solar Phys., Online First, Feb. 2011, DOI 10.1007/s11207-011-9714-9
Last Modified: 2011-06-30 06:51
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Publication Status: A&A (in press)
Last Modified: 2011-12-15 15:57
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Flare Physics in the Hinode Era (Keynote)
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David E McKenzie Submitted: 2009-05-19 16:13
Hinode's manifest of instrumentation was conceived to investigate the magnetic connections through the photosphere, lower atmosphere, and corona. The complementarity of the instruments is indeed useful, as demonstrated in numerous flares and eruptions in just the first two years of operation. I will review some of the findings from Hinode's observations of flares to date.
It is true, of course, that Hinode's capabilities have evolved since launch. These changes cause the planning of observations to be more complex, and the analysis to be less straightforward; but they do not diminish Hinode's ability to produce important observations of solar flares. On the contrary, Hinode is poised to make truly surprising discoveries. I will explain why this is so, and why we should look ... [READ MORE]
Authors: David E. McKenzie
Projects: Hinode/EIS,Hinode/SOT,Hinode/XRT
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Publication Status: Accepted for publication in Hinode-2 proceedings.
Last Modified: 2009-05-20 09:24
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Publication Status: accepted to ApJL
Last Modified: 2011-05-18 10:40
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First Simultaneous Observation of H-alpha Moreton Wave, EUV Wave, and Filament/Prominence Oscillations
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Ayumi Asai Submitted: 2011-12-27 00:40
This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.
Authors: Asai, A., Ishii, T.T., Kitai R., Ichimoto, K., UeNo, S., Nagata, S., Morita, S., Nishida, K., Shiota, D., Oi, A., Akioka, M., Shibata, K.
Projects: SDO-AIA,STEREO
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Publication Status: accepted by ApJL
Last Modified: 2011-12-28 12:07
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Publication Status: ApJ (accepted)
Last Modified: 2011-08-23 08:55
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Publication Status: ApJ; accepted
Last Modified: 2011-07-06 09:16
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Publication Status: ApJ, in press
Last Modified: 2011-05-17 19:26
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Publication Status: Accepted, A&A
Last Modified: 2011-11-22 03:20
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Publication Status: Accepted for publication in ApJL
Last Modified: 2011-09-25 05:08
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Publication Status: Solar Physics, Volume 273, Number 2, pp.403-412, DOI: 10.1007/s11207-011-9822-6
Last Modified: 2011-11-17 09:28
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Publication Status: ASP Conference Proceedings, vol.383, pp. 335-342, 2008, Proceedings of the 24th NSO Workshop, Subsurface and Atmospheric Influences on Solar Activity
Last Modified: 2012-01-11 14:26
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Publication Status: Accepted for publication in A&A
Last Modified: 2011-07-18 10:58
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Publication Status: Solar Physics 272, 137-157, DOI: 10.1007/s11207-011-9811-9, 2011
Last Modified: 2011-08-30 10:49
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Publication Status: To be published online on Wednesday, June 29. It will appear in print in the July 20, 2011 issue (736/1)
Last Modified: 2011-06-30 06:51
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Publication Status: ApJ (in press)
Last Modified: 2011-07-08 11:23
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Publication Status: A&A, accepted
Last Modified: 2011-09-08 09:32
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Height structure of X-ray, EUV and white-light emission in a solar flare
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Marina Battaglia Submitted: 2011-07-21 03:56
Context. The bulk of solar flare emission originates from very compact sources located in the lower solar atmosphere and observable at a broad range of wavelengths such as near optical, UV, EUV, soft and hard X-rays, and gamma-rays. Nevertheless, very few spatially resolved imaging observations have been performed to determine the structure of these compact regions. Aims: We investigate the above-the-photosphere heights of hard X-ray (HXR), EUV, and white-light (6173 Å) continuum sources in the low atmosphere and the corresponding densities at these heights. By considering the collisional transport of solar energetic electrons, we also determine where and how much energy is deposited and compare these values with the emissions observed in HXR, EUV, and the continuum. ... [READ MORE]
Authors: Marina Battaglia, Eduard P. Kontar
Projects: RHESSI,SDO-AIA,SDO-HMI
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Publication Status: Astronomy & Astrophysics Letters, accepted
Last Modified: 2011-07-21 08:42
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Plasmoid Releases in the Heliospheric Current Sheet and Associated Coronal Hole Boundary Layer Evolution
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Claire Foullon Submitted: 2011-05-17 12:13
This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.
Authors: Foullon, C., Lavraud, B., Luhmann, J.G., Farrugia, C.J., Retinò, A., Simunac, K.D.C., Wardle, N.C., Galvin, A.B., Kucharek, H., Owen, C.J., Popecki, M., Opitz, A. and Sauvaud, J.-A.
Projects: SoHO-LASCO,STEREO
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Publication Status: ApJ (in press)
Last Modified: 2011-05-17 19:26
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Publication Status: ApJ, In press
Last Modified: 2011-07-12 11:14
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Publication Status: accepted for publication in ApJ
Last Modified: 2011-11-08 09:00
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Publication Status: ApJL (in press)
Last Modified: 2011-09-27 10:19
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Publication Status: Accepted by ApJ
Last Modified: 2012-01-16 21:07
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Spatially resolved observations of a split-band coronal type-II radio burst
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Ivan Zimovets Submitted: 2012-08-28 02:59
Context. The origin of coronal type-II radio bursts and of their band-splitting are still not fully understood.
Aims. To make progress in solving this problem on the basis of one extremely well observed solar eruptive event.
Methods. The relative dynamics of multi-thermal eruptive plasmas, observed in detail by the SDO/AIA and of the harmonic type-II burst sources, observed by the NRH at ten frequencies from 445 to 151 MHz, is studied for the partially behind the limb event on 3 November 2010. Special attention is given to the band-splitting of the burst. Analysis is supplemented by investigation of coronal hard X-ray (HXR) sources observed by the RHESSI.
Results. It is found that the flare impulsive phase was accompanied by the formation of a double coronal HXR source, whose ... [READ MORE]
Authors: I. Zimovets, N. Vilmer, A. C.-L. Chian, I. Sharykin, A. Struminsky
Projects: Nan?ay Radioheliograph,RHESSI,SDO-AIA
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Publication Status: A&A (accepted)
Last Modified: 2012-08-28 12:33
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Enhancement of a sunspot light wall with external disturbances
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Shuhong Yang Submitted: 2016-11-30 21:39
Based on the Interface Region Imaging Spectrograph observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface, and hits the light bridge (i.e., the base of the light wall), then sudden brightenings appear at the wall base followed by the rise of wall top, leading to an increase of the wall height. Once the brightness of the wall base fades, the height of the light wall begins to decrease. Five hours later, another nearby flare takes place, a bright channel is formed that extends from the flare towards the light bridge. Although no obvious material flow along the bright channel is found, some ejected ... [READ MORE]
Authors: Shuhong Yang, Jun Zhang, Robert Erd?lyi
Projects: IRIS,SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in ApJL
Last Modified: 2016-12-14 13:55
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Publication Status: accepted for publication in Solar Physics
Last Modified: 2012-03-28 12:44
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Publication Status: ApJ Letters (in press)
Last Modified: 2013-07-19 10:35
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Publication Status: Solar Physics, submitted
Last Modified: 2015-05-12 14:02
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Geoeffectiveness of halo coronal mass ejections
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Nat Gopalswamy Submitted: 2007-02-10 05:21
We studied the geoeffectiveness, speed, solar source, and flare association of a set of 378 halo coronal mass ejections (CMEs) of cycle 23 (1996-2005, inclusive). We compiled the minimum Dst values occurring within 1-5 days after the CME onset. We compared the distributions of such Dst values for the following subsets of halo CMEs: disk halos (within 45 deg from disk center), limb halos (beyond 45 degrees but within 90 deg from disk center), and backside halo CMEs. On the average, the disk halos are followed by intense storms, limb halos are followed by moderate storms, and backside halos are not followed by significant storms. The Dst distribution for a random sample is nearly identical to the case of backside halos. We found that ~71% of all frontside halos are geoeffective, supporting ... [READ MORE]
Authors: N. Gopalswamy, S. Yashiro, and S. Akiyama
Projects: SoHO-LASCO
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Publication Status: JGR accepted Feb 7, 2007
Last Modified: 2007-02-10 08:29
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Publication Status: Solar Physics (in press)
Last Modified: 2013-04-03 12:09
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Shock Connectivity in the August 2010 and July 2012 Solar Energetic Particle Events Inferred from Observations and ENLIL Modeling
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Hazel Bain Submitted: 2016-06-28 13:36
During periods of increased solar activity, coronal mass ejections (CMEs) can occur in close succession and proximity to one another. This can lead to the interaction and merger of CME ejecta as they propagate in the heliosphere. The particles accelerated in these shocks can result in complex solar energetic particle (SEP) events, as observing spacecraft form both remote and local shock connections. It can be challenging to understand these complex SEP events from in situ profiles alone. Multipoint observations of CMEs in the near-Sun environment, from the Solar Terrestrial Relations Observatory-Sun Earth Connection Coronal and Heliospheric Investigation and the Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph, greatly improve our chances of ... [READ MORE]
Authors: H. M. Bain, M. L. Mays, J. G. Luhmann, Y. Li, L. K. Jian, and D. Odstrcil
Projects: ACE,SoHO-LASCO,STEREO
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Publication Status: Published
Last Modified: 2016-06-29 13:47
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Publication Status: A&A (in press), 2011
Last Modified: 2011-11-03 15:21
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Publication Status: A&A, 529, A123.
Last Modified: 2011-04-15 08:06
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Publication Status: Geophysical Research Letters Vol. 40 (16), pp. 4154 ? 4159
Last Modified: 2013-09-30 10:00
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Publication Status: Accepted for publication in The Astrophysical Journal
Last Modified: 2019-08-21 14:20
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Publication Status: Accepted by ApJ
Last Modified: 2013-10-31 08:18
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Anti-parallel EUV flows observed along active region filament threads with Hi-C
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Caroline Alexander Submitted: 2013-06-24 07:25
Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from H-alpha and cool EUV lines (e.g., 304A) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of `counter-steaming' flows has previously been inferred from these cool plasma observations but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193A). In this work we present observations of an active region filament observed with Hi-C that exhibits anti-parallel flows along adjacent filament threads. Complementary ... [READ MORE]
Authors: Caroline E. Alexander, Robert W. Walsh, Stephane Regnier, Jonathan Cirtain, Amy R. Winebarger, Leon Golub, Ken Kobayashi, Simon Platt, Nick Mitchell, Kelly Korreck, Bart DePontieu, Craig DeForest, Mark Weber, Alan Title, Sergey Kuzin
Projects: Other,SDO-AIA
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Publication Status: Published in ApJ, 775, L32
Last Modified: 2013-09-13 09:55
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Quasi-periodic Fast-mode Wave Trains Within a Global EUV Wave and Sequential Transverse Oscillations Detected by SDO/AIA
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Wei Liu Submitted: 2012-04-25 09:50
We present the first unambiguous detection of quasi-periodic wave trains within the broad pulse of a global EUV wave (so-called ''EIT wave'') occurring on the limb. These wave trains, running ahead of the lateral CME front of 2-4 times slower, coherently travel to distances $>R_{sun}/2$ along the solar surface, with initial velocities up to 1400 km/s decelerating to ~650 km/s. The rapid expansion of the CME initiated at an elevated height of 110 Mm produces a strong downward and lateral compression, which may play an important role in driving the primary EUV wave and shaping its front forwardly inclined toward the solar surface. The waves have a dominant 2 min periodicity that matches the X-ray flare pulsations, suggesting a causal connection. The arrival of the leading EUV wave front at ... [READ MORE]
Authors: Wei Liu, Leon Ofman, Nariaki V. Nitta, Markus J. Aschwanden, Carolus J. Schrijver, Alan M. Title, and Theodore D. Tarbell
Projects: SDO-AIA
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Publication Status: Accepted by ApJ, Apr 24, 2012
Last Modified: 2012-04-25 12:18
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Quasi-periodic Fast-mode Magnetosonic Wave Trains Within Coronal Waveguides Associated with Flares and CMEs
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Wei Liu Submitted: 2015-12-22 22:42
Quasi-periodic, fast-mode, propagating wave trains (QFPs) are a new observational phenomenon recently discovered in the solar corona by the Solar Dynamics Observatory with extreme ultraviolet (EUV) imaging observations. They originate from flares and propagate at speeds up to ~2000 km/s within funnel-shaped waveguides in the wakes of coronal mass ejections (CMEs). QFPs can carry sufficient energy fluxes required for coronal heating during their occurrences. They can provide new diagnostics for the solar corona and their associated flares. We present recent observations of QFPs focusing on their spatio-temporal properties, temperature dependence, and statistical correlation with flares and CMEs. Of particular interest is the 2010-Aug-01 C3.2 flare with correlated QFPs and drifting zebra ... [READ MORE]
Authors: Wei Liu, Leon Ofman, Brittany Broder, Marian Karlicky, and Cooper Downs
Projects: IRIS,RHESSI,SDO-AIA
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Publication Status: Accepted to the Proceedings of the 14th International Solar Wind Conference
Last Modified: 2015-12-23 12:23
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Global Energetics of Solar Flares: IV. Coronal Mass Ejection Energetics
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Markus J. Aschwanden Submitted: 2016-05-16 14:50
This study entails the fourth part of a global flare energetics project, in which the mass mcme, kinetic energy Ekin, and the gravitational potential energy Egrav of coronal mass ejections (CMEs) is measured in 399 M and X-class flare events observed during the first 3.5 yrs of the Solar Dynamics Observatory (SDO) mission, using a new method based on the EUV dimming effect. The EUV dimming is modeled in terms of a radial adiabatic expansion process, which is fitted to the observed evolution of the total emission measure of the CME source region. The model derives the evolution of the mean electron density, the emission measure, the bulk plasma expansion velocity, the mass, and the energy in the CME source region. The EUV ... [READ MORE]
Authors: Aschwanden, M.J.
Projects: SDO-AIA
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Publication Status: ApJ, subm. 2016 May 16
Last Modified: 2016-05-16 20:09
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Publication Status: Accepted for publication in ApJ
Last Modified: 2012-08-28 12:30
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Publication Status: Accepted for publication in A&A
Last Modified: 2017-04-04 08:09
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Publication Status: ApJ (in press)
Last Modified: 2010-02-26 18:53
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Publication Status: accepted on ApJ
Last Modified: 2012-05-25 11:39
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Publication Status: accept for publication in ApJ
Last Modified: 2018-01-03 11:40
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Multiwavelength Analysis of a Solar Flare on 2002 April 15
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Linhui Sui Submitted: 2005-09-30 08:28
We carried out a multiwavelength analysis of the solar limb flare on 2002 April 15. The observations all indicate that the flare occurred in an active region with an asymmetric dipole magnetic configuration. The earlier conclusion that magnetic reconnection is occurring in a large-scale current sheet in this flare is further supported by these observations: (1) Several blob-like sources, seen in RHESSI 12-25 keV X-ray images later in the flare, appeared along a line above the flare loops. These indicate the continued presence of the current sheet and are likely to be magnetic islands in the stretched sheet produced by the tearing-mode instability. (2) A cusp-like structure is seen in NoRH 34 GHz microwave images around the time of the peak flare emission. We quantitatively demonstrate ... [READ MORE]
Authors: Sui, L, Holman, G. D., White, S. M., Zhang, J.
Projects: RHESSI,Soho-MDI,Soho-LASCO,TRACE
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Publication Status: ApJ, in press (Issue of Novermber 10)
Last Modified: 2005-09-30 08:28
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Multiwavelength Observations of a Slow Raise, Multi-Step X1.6 Flare and the Associated Eruption
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Vasyl Yurchyshyn Submitted: 2015-09-21 11:30
Using multi-wavelength observations we studied a slow rise, multi-step X1.6 flare that began on November 7, 2014 as a localized eruption of core fields inside a $\delta$-sunspot and later engulfed the entire active region. This flare event was associated with formation of two systems of post eruption arcades and several J-shaped flare ribbons showing extremely fine details, irreversible changes in the photospheric magnetic fields, and it was accompanied by a fast and wide coronal mass ejection. Data from the Solar Dynamics Observatory, IRIS spacecraft along with the ground based data from the New Solar Telescope (NST) present evidence that i) the flare and the eruption were directly triggered by a flux emergence that occurred inside a $\delta$--sunspot at the boundary between two umbrae; ... [READ MORE]
Authors: Yurchyshyn, V., Kumar, P., Cho, K.S., Lim, E.K., & Abramenko, V.
Projects: IRIS,SDO-AIA,SDO-HMI
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Publication Status: ApJ., accepted
Last Modified: 2015-09-23 13:32
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Ultra-narrow Negative Flare Front Observed in Helium-10830~\AA\ using the 1.6 m New Solar Telescope
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Yan Xu Submitted: 2016-01-21 17:20
Solar flares are sudden flashes of brightness on the Sun and are often associated with coronal mass ejections and solar energetic particles which have adverse effects in the near Earth environment. By definition, flares are usually referred to bright features resulting from excess emission. Using the newly commissioned 1.6~m New Solar Telescope at Big Bear Solar Observatory, here we show a striking ``negative'' flare with a narrow, but unambiguous ``dark'' moving front observed in \ion{He}{1} 10830~\AA, which is as narrow as 340 km and is associated with distinct spectral characteristics in H$\alpha$ and \ion{Mg}{2} lines. Theoretically, such negative contrast in \ion{He}{1} 10830~\AA\ can be produced under special circumstances, by nonthermal-electron collisions, or photoionization ... [READ MORE]
Authors: Yan Xu, Wenda Cao, Mingde Ding, Lucia Kleint, Jiangtao Su, Chang Liu, Haisheng Ji, Jongchul Chae, Ju Jing, Kyuhyoun Cho, Kyungsuk Cho, Dale Gary, and Haimin Wang
Projects: IRIS,Other,SDO-AIA,SDO-HMI
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Publication Status: accepted by ApJ
Last Modified: 2016-01-26 21:32
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Publication Status: A&A, in press
Last Modified: 2018-09-04 09:19
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An Observationally-Constrained Model of a Flux Rope that Formed in the Solar Corona
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Alexander James Submitted: 2018-02-27 09:22
Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the coronae of stars. Understanding the plasma processes involved in CME initiation has applications to space weather forecasting and laboratory plasma experiments. James et al. (Sol. Phys. 292, 71, 2017) used EUV observations to conclude that a magnetic flux rope formed in the solar corona above NOAA Active Region 11504 before it erupted on 14 June 2012 (SOL2012-06-14). In this work, we use data from the Solar Dynamics Observatory to model the coronal magnetic field of the active region one hour prior to eruption using a nonlinear force-free field extrapolation, and find a flux rope reaching a maximum height of 150 Mm above the photosphere. Estimations of the average twist of the strongly asymmetric extrapolated flux ... [READ MORE]
Authors: James, A. W., Valori, G., Green, L. M., Liu, Y., Cheung, M. C. M., Guo, Y., van Driel-Gesztelyi, L.
Projects: SDO-AIA,SDO-HMI
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Publication Status: Accepted in ApJL
Last Modified: 2018-02-28 14:01
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Analysis of a global Moreton wave observed on October 28, 2003
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Nicole Muhr Submitted: 2009-11-24 04:29
We study the well pronounced Moreton wave that occurred in association with the X17.2
flare/CME event of October 28, 2003. This Moreton wave is striking for its global propagation and
two separate wave centers, which implies that two waves were launched simultaneously. The mean
velocity of the Moreton wave, tracked within different sectors of propagation direction, lies in the
range of v ~ 900 − 1100 km/s with two sectors showing wave deceleration. The perturbation
profile analysis of the wave indicates amplitude growth followed by amplitude weakening and
broadening of the perturbation profile, which is consistent with a disturbance first driven and
then evolving into a freely propagating wave. The EIT wavefront is found to lie on the same
kinematical curve as the Moreton ... [READ MORE]
Authors: N. Muhr, B. Vrsnak, M. Temmer, A. M. Veronig, J. Magdalenic
Projects: None,SoHO-EIT,SoHO-MDI,SoHO-LASCO,TRACE
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Publication Status: accepted for ApJ
Last Modified: 2009-11-24 12:36
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Publication Status: A&A (accepted)
Last Modified: 2017-01-19 13:31
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Reconnection and energy release rates in a two-ribbon flare
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Christiane Miklenic Submitted: 2006-10-05 03:35
The aim of this study was to derive the local reconnection rate (coronal electric field) and the global reconnection rate (magnetic flux change rate), as well as the energy release rate (Poynting flux), in a two-ribbon flare
from chromospheric/photospheric observations. Furthermore, we tested whether equal shares of positive and negative magnetic flux are involved in the flare process.
A well-observed GOES M3.9 two-ribbon flare was analyzed. The required observables (ribbon expansion velocity, newly brightened area, and magnetic field strength at the ribbon front) were extracted from the TRACE 1600 A and Kanzelhoehe
H-alpha image time series, and a SOHO MDI magnetogram. Furthermore, the ratio of the converted positive vs. negative magnetic flux was determined. Both RHESSI ... [READ MORE]
Authors: Miklenic, C. H., Veronig, A. M., Vrsnak, B., and Hanslmeier, A.
Projects: RHESSI,SoHO-MDI,TRACE
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Publication Status: A&A (accepted)
Last Modified: 2006-10-18 03:54
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An Early Diagnostics of the Geoeffectiveness of Solar Eruptions from Photospheric Magnetic Flux Observations: The Transition from SOHO to SDO
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Ilya Chertok Submitted: 2017-02-20 23:55
In our previous articles (Chertok et al.: 2013, Solar Phys. 282, 175, and 2015, Solar Phys. 290, 627), we presented a preliminary tool for the early diagnostics of the geoeffectiveness of solar eruptions based on the estimate of the total unsigned line-of-sight photospheric magnetic flux in accompanying extreme-ultraviolet arcades and dimmings. This tool was based on the analysis of eruptions observed in 1996-2005 with SOHO/EIT and MDI. Empirical relationships were obtained to estimate the probable importance of upcoming space weather disturbances caused by an eruption, which just occurred, without data on the associated coronal mass ejections. It was possible to estimate the intensity of a non-recurrent geomagnetic storm (GMS) and Forbush decrease (FD), as well as their onset and peak ... [READ MORE]
Authors: I.M. Chertok, V.V. Grechnev, A.A. Abunin
Projects: SDO-AIA,SDO-HMI,SoHO-EIT,SoHO-MDI
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Publication Status: Solar Physics, accepted
Last Modified: 2017-02-21 15:43
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Publication Status: Accepted by ApJ Letter (2012)
Last Modified: 2012-04-10 11:29
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Turbulent kinetic energy in the energy balance of a solar flare
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Eduard Kontar Submitted: 2017-04-01 08:49
The energy released in solar flares derives from a reconfiguration of magnetic fields to a lower energy state, and is manifested in several forms, including bulk kinetic energy of the coronal mass ejection, acceleration of electrons and ions, and enhanced thermal energy that is ultimately radiated away across the electromagnetic spectrum from optical to X-rays. Using an unprecedented set of coordinated observations, from a suite of instruments, we here report on a hitherto largely overlooked energy component -- the kinetic energy associated with small-scale turbulent mass motions. We show that the spatial location of, and timing of the peak in, turbulent kinetic energy together provide persuasive evidence that turbulent energy may play a key role in the transfer of energy in solar flares. ... [READ MORE]
Authors: Kontar, E. P.; Perez, J. E.; Harra, L. K.; Kuznetsov, A. A.; Emslie, A. G.; Jeffrey, N. L. S.; Bian, N. H.; Dennis, B. R.
Projects: None,Hinode/EIS,RHESSI,SDO-AIA,SDO-HMI
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Publication Status: to be published in Physical Review Letters
Last Modified: 2017-04-02 19:06
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Publication Status: accepted for publication in The Astrophysical Journal
Last Modified: 2013-04-17 12:20
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Interplanetary shocks lacking type II radio bursts
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Nat Gopalswamy Submitted: 2010-01-18 14:06
We report on the radio-emission characteristics of 222 interplanetary (IP) shocks. A surprisingly large fraction of the IP shocks (~34%) is radio quiet (i.e., the shocks lacked type II radio bursts). The CMEs associated with the RQ shocks are generally slow (average speed ~535 km/s) and only ~40% of the CMEs were halos. The corresponding numbers for CMEs associated with radio loud (RL) shocks are 1237 km/s and 72%, respectively. The RQ shocks are also accompanied by lower peak soft X-ray flux. CMEs associated with RQ (RL) shocks are generally accelerating (decelerating). The kinematics of CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock The RQ shocks seem to be mostly subcritical and ... [READ MORE]
Authors: N. Gopalswamy, H. Xie, P. Makela, S. Akiyama, S. Yashiro, M. L. Kaiser, R. A. Howard, J.-L. Bougeret
Projects: SoHO-LASCO
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Publication Status: Astrophys. J. in press
Last Modified: 2010-01-19 09:08
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Publication Status: Space Weather (accepted)
Last Modified: 2004-10-13 09:41
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Publication Status: Published by A&A (movie available in electronic version)
Last Modified: 2013-04-26 10:14
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Orientations of LASCO Halo CMEs and Their Connection to the Flux Rope Structure of Interplanetary CMEs
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Vasyl Yurchyshyn Submitted: 2007-01-25 15:46
Coronal mass ejections (CMEs) observed near the Sun via LASCO coronographic imaging are the most important solar drivers of geomagnetic storms. ICMEs, their interplanetary, near-Earth counterparts, can be detected in-situ, for example, by the Wind and ACE spacecraft. An ICME usually exhibits a complex structure that very often includes a magnetic cloud (MC). They can be commonly modelled as magnetic flux ropes and there is observational evidence to expect that the orientation of a halo CME elongation corresponds to the orientation of the flux rope. In this study, we compare orientations of elongated CME halos and the corresponding MCs, measured by Wind and ACE spacecraft. We characterize the MC structures by using the Grad-Shafranov reconstruction technique and three MC fitting methods to ... [READ MORE]
Authors: V. Yurchyshyn, Q.Hu, R.P. Lepping, B.J. Lynch & J. Krall
Projects: SoHO-LASCO
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Publication Status: Adv. Space Res., http://dx.doi.org/10.1016/j.asr.2007.01.059
Last Modified: 2007-02-12 10:47
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Preconditioning of interplanetary space due to transient CME disturbances
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Manuela Temmer Submitted: 2016-12-20 01:38
Interplanetary space is characteristically structured mainly by high-speed solar wind streams emanating from coronal holes and transient disturbances such as coronal mass ejections (CMEs). While high-speed solar wind streams pose a continuous outflow, CMEs abruptly disrupt the rather steady structure causing large deviations from the quiet solar wind conditions. For the first time, we give a quantification of the duration of disturbed conditions (preconditioning) for interplanetary space caused by CMEs. To this aim, we investigate the plasma speed component of the solar wind and the impact of in situ detected CMEs (ICMEs), compared to different background solar wind models (ESWF, WSA, persistence model) for the time range 2011-2015. We quantify in terms of standard error measures the ... [READ MORE]
Authors: M. Temmer, M. A. Reiss, L. Nikolic, S. J. Hofmeister, A. M. Veronig
Projects: ACE
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Publication Status: Accepted for publication in The Astrophysical Journal
Last Modified: 2016-12-21 12:21
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Evidence of Rapid Flux Emergence Associated with the M8.7 Flare on 2003 July 26
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Haimin Wang Submitted: 2003-11-24 20:48
In this paper, we present a detailed study of the M8.7 flare that occurred
on July 26, 2002, using data from Big Bear Solar Observatory (BBSO),
Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Transition Region
and Coronal Explorer (TRACE) and Solar and Heliospheric Observatory
(SOHO). This flare has similar interesting properties to a number of
flares that we studied previously, such as a rapid increase of magnetic
flux in one polarity, and an increase in transverse fields and magnetic
shear associated with the flare. However, this event had most
comprehensive observations, in particular, the high resolution high
cadence BBSO vector magnetograph observations. At the time of the flare,
across the flare neutral line, there was a sudden emergence of magnetic
flux at the ... [READ MORE]
Authors: H. Wang, J. Qiu, J. Jing, T. Spirock, V. Yurchyshyn, V. Abramenko, H. Ji and P.R. Goode
Projects: RHESSI,Soho-MDI,TRACE
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Publication Status: ApJ, (submitted)
Last Modified: 2003-11-24 20:48
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Publication Status: Accepted for publication to ApJ Letters
Last Modified: 2019-12-04 11:28
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Imaging Spectroscopy of Solar Radio Burst Fine Structures
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Eduard Kontar Submitted: 2017-11-16 00:25
Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio-wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the LOw Frequency Array (LOFAR), an instrument with high time resolution that also permits imaging at scales much shorter than those corresponding to radio-wave propagation in the corona. The observations demonstrate that radio-wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed ... [READ MORE]
Authors: E. P. Kontar, S. Yu, A. A. Kuznetsov, A. G. Emslie, B. Alcock, N. L. S. Jeffrey, V. N. Melnik, N. H. Bian, P. Subramanian
Projects: Other,SDO-AIA
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Publication Status: https://www.nature.com/articles/s41467-017-01307-8
Last Modified: 2017-11-16 23:31
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The Thermal Properties of Solar Flares over Three Solar Cycles Using GOES X-Ray Observations
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Daniel Ryan Submitted: 2012-05-31 10:13
Solar flare X-ray emission results from rapidly increasing temperatures and emission measures in flaring active region loops. To date, observations from the X-Ray Sensor (XRS) onboard the Geostationary Operational Environmental Satellite (GOES) have been used to derive these properties, but have been limited by a number of factors, including the lack of a consistent background subtraction method capable of being automatically applied to large numbers of flares. In this paper, we describe an automated temperature and emission measure-based background subtraction method (TEBBS), which builds on the methods of Bornmann (1990). Our algorithm ensures that the derived temperature is always greater than the instrumental limit and the pre-flare background temperature, and that the temperature and ... [READ MORE]
Authors: Daniel F. Ryan, Ryan O. Milligan, Peter T. Gallagher, Brian R. Dennis, A. Kim Tolbert, Richard A. Schwartz, C. Alex Young
Projects: GOES X-rays
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Publication Status: ApJS (accepted 2012-05-24)
Last Modified: 2012-05-31 16:01
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The energetics of a global shock wave in the low solar corona
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David Long Submitted: 2015-01-08 04:10
As the most energetic eruptions in the solar system, coronal mass ejections (CMEs) can produce shock waves at both their front and flanks as they erupt from the Sun into the heliosphere. However, the amount of energy produced in these eruptions, and the proportion of their energy required to produce the waves, is not well characterised. Here we use observations of a solar eruption from 2014 February 25 to estimate the energy budget of an erupting CME and the globally-propagating "EIT wave" produced by the rapid expansion of the CME flanks in the low solar corona. The "EIT wave" is shown using a combination of radio spectra and extreme ultraviolet images to be a shock front with a Mach number greater than one. Its initial energy is then calculated using the Sedov-Taylor blast-wave ... [READ MORE]
Authors: David M. Long, Deborah Baker, David R. Williams, Eoin P. Carley, Peter T. Gallagher, Pietro Zucca
Projects: Hinode/EIS,SDO-AIA
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Publication Status: Accepted for publication in ApJ
Last Modified: 2015-01-09 12:50
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Observational Evidence of Magnetic Reconnection for Brightenings and Transition Region Arcades in IRIS observations
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Jie Zhao Submitted: 2017-01-30 20:21
By using a new method of forced-field extrapolation, we study the emerging flux region AR 11850 observed by the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamical Observatory (SDO). Our results suggest that the bright points (BPs) in this emerging region have responses in lines formed from the upper photosphere to the transition region, with a relatively similar morphology. They have an oscillation of several minutes according to the Atmospheric Imaging Assembly (AIA) data at 1600 and 1700 A . The ratio between the BP intensities measured in 1600 A and 1700 A filtergrams reveals that these BPs are heated differently. Our analysis of the Helioseismic and Magnetic Imager (HMI) vector magnetic field and the corresponding topology in AR11850 indicates that the BPs are located at ... [READ MORE]
Authors: Jie Zhao, Brigitte Schmieder, Hui Li, Etienne Pariat, Xiaoshuai Zhu, Li Feng, Michalina Grubecka
Projects: IRIS,SDO-AIA,SDO-HMI
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Publication Status: Accepted by ApJ. In Press.
Last Modified: 2017-01-31 11:46
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Modeling Magnetic Field Structure of a Solar Active Region Corona using Nonlinear Force-Free Fields in Spherical Geometry
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Yang Guo Submitted: 2012-10-21 08:16
We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all boundaries, to cases where noisy vector data are provided on only the lower boundary (approximating the solar problem). Analytical tests also show that the NLFFF code in the spherical geometry performs better than that in the Cartesian one when the field of view of the bottom boundary is large, say, $20^circ imes 20^circ$. Additionally, We apply the NLFFF model to an active region observed by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) both before and after an M8.7 flare. For each observation time, we initialize ... [READ MORE]
Authors: Y. Guo, M. D. Ding, Y. Liu, X. D. Sun, M. L. DeRosa, T. Wiegelmann
Projects: SDO-AIA,SDO-HMI
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Publication Status: accepted for publication in ApJ
Last Modified: 2012-10-22 10:26
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Observation of Loop Connectivity Change in a Solar Flare Triggered by Loop-Loop Interaction
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Linhui Sui Submitted: 2005-09-30 08:37
Magnetic reconnection between two adjacent magnetic loops or arcades has been a longstanding model for solar flares. However, the observations supporting this quadrupolar flare model are mainly post-reconnection observations. We present a set of flare observations in EUV, X-rays and Há which shows that a pre-flare loop changed its connectivity soon after the start of an M1 flare on June 2, 2002. A large arcade of loops seen in EUV expanded slowly at ~6 km/s about 3 min before the start of the flare. Another smaller EUV loop expanded rapidly at ~100 km/s at the start of the flare. After ~20 s, the smaller loop then reconnected with magnetic loops within the arcade, resulting in two new post-reconnection loops. The newly-formed, smaller EUV loop, with a long cusp at the looptop, was also ... [READ MORE]
Authors: Sui, L., Holman, G. D., Dennis, B. R.
Projects: RHESSI,Soho-MDI,TRACE
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Publication Status: submitted to ApJ
Last Modified: 2005-09-30 08:37
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Maximum CME speed as an indicator of solar and geomagnetic activities
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Ali Kilcik Submitted: 2011-11-18 12:31
We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the ... [READ MORE]
Authors: A. Kilcik, V.B. Yurchyshyn, V. Abramenko, P.R. Goode, N. Gopalswamy, A. Ozguc, J.P. Rozelot
Projects: SoHO-LASCO
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Publication Status: Published in 2011, Astrophys. J. 727, article id. 44 DOI: 10.1088/0004-637X/727/1/44
Last Modified: 2011-11-22 02:49
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Publication Status: The Astrophysical Journal, Volume 763, Issue 1, article id. 24, 12 pp. (2013).
Last Modified: 2013-04-30 12:04
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Studies of Isolated and Non-isolated Photospheric Bright Points in an Active Region Observed by the New Vacuum Solar Telescope
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Yanxiao Liu Submitted: 2018-03-25 22:15
Properties of photospheric bright points (BPs) near an active region have been studied in TiO λ 7058 ? images
observed by the New Vacuum Solar Telescope of the Yunnan Observatories. We developed a novel recognition
method that was used to identify and track 2010 BPs. The observed evolving BPs are classified into isolated
(individual) and non-isolated (where multiple BPs are observed to display splitting and merging behaviors) sets.
About 35.1% of BPs are non-isolated. For both isolated and non-isolated BPs, the brightness varies from 0.8 to 1.3
times the average background intensity and follows a Gaussian distribution. The lifetimes of BPs follow a lognormal distribution, with characteristic lifetimes of (267 ? 140) s and (421 ? 255) s, respectively. Their size also follows ... [READ MORE]
Authors: Yanxiao Liu, Yongyuan Xiang, Robertus Erd?lyi, Zhong Liu, Dong Li, Zongjun Ning, Yi Bi,Ning Wu, and Jun Lin
Projects: New Vacuum Solar Telescope (NVST)
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Publication Status: Accepted for publication in ApJ
Last Modified: 2018-03-28 11:37
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Publication Status: J. of Atmospheric and Solar-Terrestrial Physics, 70, 2078 - 2100, 2008, doi:10.1016/j.jastp.2008.06.010
Last Modified: 2009-01-05 14:14
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Publication Status: Article accepted for publication in Section 9. The Sun of Astronomy and Astrophysics. The official date of acceptance is 13/09/2011.
Last Modified: 2012-11-12 03:57
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Near-Sun Flux Rope Structure of CMEs
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Hong Xie Submitted: 2013-01-07 13:08
We have used the Krall's flux-rope model (Krall and St. Cyr, Astrophys.
J. 2006, 657, 1740) (KFR) to fit 23 magnetic cloud (MC)-CMEs and
30 non-cloud ejecta (EJ)-CMEs in the Living With a Star (LWS) Coordinated
Data Analysis Workshop (CDAW) 2011 list. The KFR-fit results shows that the
CMEs associated with MCs (EJs) have been deflected closer to (away from) the
solar disk center (DC), likely by both the intrinsic magnetic structures inside an
active region (AR) and ambient magnetic structures (e.g. nearby ARs, coronal
holes, and streamers, etc.). The mean propagation latitudes and longitudes of
the EJ-CMEs (18◦, 11◦) were larger than those of the MC-CMEs (11◦, 6◦) by
7◦ and 5◦, respectively. Furthermore, the KFR-fit widths showed that the ... [READ MORE]
Authors: H. Xie, N. Gopalswamy, and O. C. St.Cyr
Projects: SoHO-EIT,SoHO-LASCO
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Publication Status: published in Solar Physics 2013
Last Modified: 2013-01-10 09:37
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How Many Twists Do Solar Coronal Jets Release?
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Jiajia Liu Submitted: 2019-05-24 07:46
Highly twisted magnetic flux ropes, with finite length, are subject to kink instabilities, and could lead to a number of eruptive phenomena in the solar atmosphere, including flares, coronal mass ejections (CMEs) and coronal jets. The kink instability threshold, which is the maximum twist a kink-stable magnetic flux rope could contain, has been widely studied in analytical models and numerical simulations, but still needs to be examined by observations. In this article, we will study twists released by 30 off-limb rotational solar coronal jets, and compare the observational findings with theoretical kink instability thresholds. We have found that: 1) the number of events with more twist release becomes less; 2) each of the studied jets has released a twist number of at least 1.3 turns (a ... [READ MORE]
Authors: Jiajia Liu, Yuming Wang, Robertus Erd?lyi
Projects: SDO-AIA
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Publication Status: Accepted for publication in Frontiers in Astronomy and Space Sciences
Last Modified: 2019-05-24 10:19
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Morphology and density of post-CME current sheets
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Bojan Vrsnak Submitted: 2009-02-25 06:18
Eruption of a coronal mass ejection (CME) drags and ''opens'' the coronal magnetic field, presumably leading to the formation of a large-scale current sheet and the field relaxation by magnetic reconnection. We analyze physical characteristics of ray-like coronal features formed in the aftermath of CMEs, to check if the interpretation of this phenomenon in terms of reconnecting current sheet is consistent with the observations. The study is focused on measurements of the ray width, density excess, and coronal velocity field as a function of the radial distance. The morphology of rays indicates that they occur as a consequence of Petschek-like reconnection in the large scale current sheet formed in the wake of CME. The hypothesis is supported by the flow pattern, often showing outflows ... [READ MORE]
Authors: Vrsnak, B., Poletto, G., Vujic, E., Vourlidas, A., Ko, Y.-K., Raymond, J. C., Ciaravella, A., Zic, T., Webb, D. F., Bemporad, A., Landini, F., Schettino, G., Jacobs, C., Suess, S. T.
Projects: SoHO-LASCO
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Publication Status: in press
Last Modified: 2009-02-25 07:57
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Publication Status: SolPhys(accepted)
Last Modified: 2009-06-20 11:56
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Publication Status: In press A&A
Last Modified: 2012-12-01 23:51
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The Relationship Between Solar Radio and Hard X-ray Emission
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Amir Caspi Submitted: 2011-10-28 12:20
This review discusses the complementary relationship between radio and hard
X-ray observations of the Sun using primarily results from the era of the
Reuven Ramaty High Energy Solar Spectroscopic Imager satellite. A primary focus
of joint radio and hard X-ray studies of solar flares uses observations of
nonthermal gyrosynchrotron emission at radio wavelengths and bremsstrahlung
hard X-rays to study the properties of electrons accelerated in the main flare
site, since it is well established that these two emissions show very similar
temporal behavior. A quantitative prescription is given for comparing the
electron energy distributions derived separately from the two wavelength
ranges: this is an important application with the potential for measuring the
magnetic field strength in the ... [READ MORE]
Authors: Stephen M. White, Arnold O. Benz, Steven Christe, Frantisek Farnik, Mukul R. Kundu, Gottfried Mann, Zongjun Ning, Jean-Pierre Raulin, Adriana V. R. Silva-Valio, Pascal Saint-Hilaire, Nicole Vilmer, Alexander Warmuth
Projects: GONG,Hinode/EIS,Hinode/SOT,Hinode/XRT,Nobeyama Radioheliograph,Owens Valley Solar Array,RHESSI,SDO-AIA,SDO-HMI,SDO-EVE,SoHO-EIT,SoHO-MDI,SoHO-CDS,SoHO-LASCO,SoHO-SUMER,STEREO,TRACE
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Publication Status: Published -- White, S. M., et al. 2011, Space Sci. Rev., 159, 225; DOI 10.1007/s11214-010-9708-1
Last Modified: 2011-11-17 14:19
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Onset of Photospheric Impacts and Helioseismic Waves in X9.3 Solar Flare of September 6, 2017
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Alexander Kosovichev Submitted: 2018-05-25 11:59
The X9.3 flare of September 6, 2017, was the most powerful flare of Solar Cycle 24. It generated strong white-light emission and multiple helioseismic waves (sunquakes). By using data from Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as well as hard X-ray data from KONUS instrument onboard WIND spacecraft, and Anti-Coincidence System (ACS) onboard the INTERGRAL space observatory, we investigate spatio-temporal dynamics of photospheric emission sources, identify sources of helioseismic waves and compare the flare photospheric dynamics with the hard X-ray (HXR) temporal profiles. The results show that the photospheric flare impacts started to develop in compact regions in close vicinity of the magnetic polarity inversion line (PIL) in the pre-impulsive ... [READ MORE]
Authors: Ivan N. Sharykin, Alexander G. Kosovichev
Projects: GOES X-rays,INTEGRAL-ACS,SDO-HMI,Wind
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Publication Status: submitted to ApJ
Last Modified: 2018-05-26 17:25
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Publication Status: To appear in proceedings of IAU Symposium 226, Coronal and Stellar Mass Ejections, Sept 13-17 2004, Beijing
Last Modified: 2005-02-07 05:51
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Publication Status: ApJ, Volume 787, Page 123, 2014
Last Modified: 2014-06-12 14:54
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Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy
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Bin Chen Submitted: 2012-12-26 09:40
We report observations of type III radio bursts at decimeter wavelengths (type IIIdm bursts) -- signatures of suprathermal electron beams propagating in the low corona -- using the new technique of radio dynamic imaging spectroscopy provided by the recently upgraded Karl G. Jansky Very Large Array (VLA). For the first time, type IIIdm bursts were imaged with high time and frequency resolution over a broad frequency band, allowing electron beam trajectories in the corona to be deduced. Together with simultaneous hard X-ray (HXR) and extreme ultraviolet (EUV) observations, we show these beams emanate from an energy release site located in the low corona at a height below ~15 Mm, and propagate along a bundle of discrete magnetic loops upward into the corona. Our observations enable direct ... [READ MORE]
Authors: Bin Chen, Timothy S. Bastian, Stephen M. White, Dale E. Gary, Richard A. Perley, Michael P. Rupen, Brent R. Carlson
Projects: RHESSI,SDO-AIA,SDO-HMI,STEREO,Very Large Array
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Publication Status: Accepted for publication in the Astrophysical Journal Letters. 6 pages, 5 figures
Last Modified: 2012-12-26 12:54
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Solar signatures and eruption mechanism of the 2010 August 14 CME
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Dan Seaton Submitted: 2017-02-06 13:45
On 2010 August 14, a wide-angled coronal mass ejection (CME) was observed. This solar eruption originated from a destabilized filament that connected two active regions and the unwinding of this filament gave the eruption an untwisting motion that drew the attention of many observers. In addition to the erupting filament and the associated CME, several other low-coronal signatures that typically indicate the occurrence of a solar eruption were associated to this event. However, contrary to what is expected, the fast CME (v>900 km s−1) was accompanied by only a weak C4.4 flare. We investigate the various eruption signatures that were observed for this event and focus on the kinematic evolution of the filament in order to determine its eruption mechanism. Had this solar eruption ... [READ MORE]
Authors: Elke D'Huys, Daniel B. Seaton, Anik De Groof, David Berghmans, Stefaan Poedts
Projects: ACE,GOES X-rays,PROBA2/SWAP,SDO-AIA,SDO-HMI,SoHO-LASCO,STEREO
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Publication Status: Accepted for publication in the Journal of Space Weather and Space Climate
Last Modified: 2017-02-07 23:56
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Publication Status: published
Last Modified: 2017-04-11 23:29
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Properties of Solar Ephemeral Regions at the Emergence Stage
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Shuhong Yang Submitted: 2013-12-02 18:46
For the first time, we statistically study the properties of ephemeral regions (ERs) and quantitatively determine their parameters at the emergence stage based on a sample of 2988 ERs observed by the Solar Dynamics Observatory. During the emergence process, there are three kinds of kinematic performances, i.e., separation of dipolar patches, shift of ER's magnetic centroid, and rotation of ER's axis. The average emergence duration, flux emergence rate, separation velocity, shift velocity, and angular speed are 49.3 min, 2.6 ? 10^15 Mx s^−1, 1.1 km s^−1, 0.9 km s^−1, and 0$degr$.6 min^−1, respectively. At the end of emergence, the mean magnetic flux, separation distance, shift distance, and rotation angle are 9.3 ? 10^18 Mx, 4.7 Mm, 1.1 Mm, and 12$degr$.9, ... [READ MORE]
Authors: Shuhong Yang, Jun Zhang
Projects: SDO-AIA,SDO-HMI
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Publication Status: accepted for publication in ApJ
Last Modified: 2013-12-03 10:15
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Publication Status: Astronomy and Astrophysics, in press
Last Modified: 2018-08-07 11:10
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Improved methods for determining the kinematics of coronal mass ejections and coronal waves
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Jason P. Byrne Submitted: 2013-07-31 18:20
Context: The study of solar eruptive events and associated phenomena is of great importance in the context of solar and heliophysics. Coronal mass ejections (CMEs) and coronal waves are energetic manifestations of the restructuring of the solar magnetic field and mass motion of the plasma. Characterising this motion is vital for deriving the dynamics of these events and thus understanding the physics driving their initiation and propagation. The development and use of appropriate methods for measuring event kinematics is therefore imperative.
Aims: Traditional approaches to the study of CME and coronal wave kinematics do not return wholly accurate nor robust estimates of the true event kinematics and associated uncertainties. We highlight the drawbacks of these approaches, and ... [READ MORE]
Authors: J. P. Byrne, D. M. Long, P. T. Gallagher, D. S. Bloomfield, S. A. Maloney, R. T. J. McAteer, H. Morgan, S. R. Habbal
Projects: SDO-AIA,SoHO-EIT,SoHO-LASCO,STEREO
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Publication Status: Accepted
Last Modified: 2013-08-01 11:17
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Publication Status: ApJ, Vol 633 (2005 Nov 1 issue, in press)
Last Modified: 2005-07-18 11:51
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Publication Status: ApJ, 2013 in press
Last Modified: 2012-12-14 16:10
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Publication Status: Accepted
Last Modified: 2015-06-29 11:55
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Publication Status: accepted for publication in ApJ
Last Modified: 2019-11-18 20:03
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A large-scale search for evidence of quasi-periodic pulsations in solar flares
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Andrew Inglis Submitted: 2016-10-24 19:30
The nature of quasi-periodic pulsations in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with quasi-periodic pulsations in solar flares, focusing on the 1 - 300s timescale. We analyse 675 M- and X-class flares observed by GOES in 1-8A soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyse Fermi/GBM 15-25 keV X-ray data for each of these flares that was associated with a Fermi/GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, ... [READ MORE]
Authors: A. R. Inglis, J. Ireland, B. R. Dennis, L. A. Hayes, P. T. Gallagher
Projects: Fermi/GBM,GOES X-rays
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Publication Status: Accepted for publication in ApJ
Last Modified: 2016-10-25 12:27
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Publication Status: ApJ (in press), astro-ph/0706.3519
Last Modified: 2007-07-08 23:25
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Publication Status: A&A Letter, 2009, in press
Last Modified: 2009-08-04 08:07
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Publication Status: ApJ (in press)
Last Modified: 2015-07-22 14:53
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Publication Status: In print
Last Modified: 2012-04-25 12:19
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Publication Status: Solar Physics (accepted)
Last Modified: 2018-11-05 14:16
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Multiwavelength observations of a partially eruptive filament on 2011 September 8
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Qingmin Zhang Submitted: 2015-03-10 19:25
In this paper, we report our multiwavelength observations of a partial filament eruption event in NOAA
active region 11283 on 2011 September 8. A magnetic null point and the corresponding spine and
separatrix surface are found in the active region. Beneath the null point, a sheared
arcade supports the filament along the highly complex and fragmented polarity inversion line. After
being activated, the sigmoidal filament erupted and
split into two parts. The major part rose at the speeds of 90$-$150 km s$^{-1}$ before
reaching the maximum apparent height of $\sim$115 Mm. Afterwards, it returned to the solar surface
in a bumpy way at the speeds of 20$-$80 km s$^{-1}$. The rising and falling motions were clearly
observed in the extreme-ultravoilet (EUV), UV, and ... [READ MORE]
Authors: Q. M. Zhang, Z. J. Ning, Y. Guo, T. H. Zhou, X. Cheng, H. S. Ji, L. Feng, T. Wiegelmann
Projects: SDO-AIA
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Publication Status: Accepted for publication in ApJ
Last Modified: 2015-03-11 14:47
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Publication Status: Published
Last Modified: 2012-06-13 15:34
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Solar Open Flux Migration from Pole to Pole: Magnetic Field Reversal
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Chia-Hsien Lin Submitted: 2017-08-27 01:58
Coronal holes are solar regions with low soft X-ray or low extreme ultraviolet intensities. The magnetic fields from coronal holes extend far away from the Sun, and thus they are identified as regions with open magnetic field lines. Coronal holes are concentrated in the polar regions during the sunspot minimum phase, and spread to lower latitude during the rising phase of solar activity. In this work,
we identify coronal holes with outward and inward open magnetic fluxes being in the opposite poles during solar quiet period. We find that during the sunspot rising phase, the outward and inward open fluxes perform pole-to-pole trans-equatorial migrations in opposite directions. The migration of the open fluxes consists of three parts: open flux areas migrating across the equator, new open ... [READ MORE]
Authors: Huang, G.-H., Lin, C.-H., and Lee, L.C.
Projects: SDO-AIA,SDO-HMI
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Publication Status: Scientific Report (published)
Last Modified: 2017-08-28 12:24
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Publication Status: accepted for publication in ApJ
Last Modified: 2018-12-28 14:32
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Publication Status: Accepted for publication in Astronomy and Astrophysics
Last Modified: 2007-01-08 22:20
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Publication Status: accepted by ApJ
Last Modified: 2012-05-02 11:16
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Charge states and FIP bias of the solar wind from coronal holes, active regions, and quiet Sun
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Maria Madjarska Submitted: 2017-01-27 00:02
Connecting in-situ measured solar-wind plasma properties with typical regions on the Sun can provide an effective constraint and test to various solar wind models. We examine the statistical characteristics of the solar wind with an origin in different types of source regions. We find that the speed distribution of coronal hole (CH) wind is bimodal with the slow wind peaking at ~400 km/s and a fast at ~600 km/s. An anti-correlation between the solar wind speeds and the O7+/O6+ ion ratio remains valid in all three types of solar wind as well during the three studied solar cycle activity phases, i.e.
solar maximum, decline and minimum. The N_Fe/N_O range and its average values all decrease with the increasing solar wind speed in different types of solar wind. The N_Fe/N_O range (0.06?0.40, ... [READ MORE]
Authors: Hui Fu, Maria S. Madjarska, LiDong Xia, Bo Li, ZhengHua Huang, Zhipeng Wangguan
Projects: ACE,SoHO-EIT,SoHO-MDI
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Publication Status: accepted for publication in ApJ
Last Modified: 2017-01-31 11:46
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Publication Status: The Astrophysical Journal Letters, Volume 765, Issue 2, article id. L42, 7 pp. (2013).
Last Modified: 2013-04-30 12:03
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Genesis and impulsive evolution of the 2017 September 10 coronal mass ejection
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Astrid Veronig Submitted: 2018-10-24 07:31
The X8.2 event of 10 September 2017 provides unique observations to study the genesis, magnetic morphology and impulsive dynamics of a very fast CME. Combining GOES-16/SUVI and SDO/AIA EUV imagery, we identify a hot ($T\approx 10-15$ MK) bright rim around a quickly expanding cavity, embedded inside a much larger CME shell ($T\approx 1-2$ MK). The CME shell develops from a dense set of large AR loops
($\gtrsim$0.5~$R_s$), and seamlessly evolves into the CME front observed in LASCO C2.
The strong lateral overexpansion of the CME shell acts as a piston initiating the fast EUV wave. The hot cavity rim is demonstrated to be a manifestation of the dominantly poloidal flux and frozen-in plasma added to the rising flux rope by magnetic reconnection in the current sheet beneath. The same ... [READ MORE]
Authors: Astrid M. Veronig, Tatiana Podladchikova, Karin Dissauer, Manuela Temmer, Daniel B. Seaton, David Long, Jingnan Guo, Bojan Vrsnak, Louise Harra, Bernhard Kliem
Projects: GOES X-rays,SDO-AIA
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Publication Status: ApJ (accepted)
Last Modified: 2018-10-24 10:42
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A Truly Global EUV Wave From the SOL2017-09-10 X8.2 Solar Flare-CME Eruption
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Wei Liu Submitted: 2018-07-25 10:19
We report SDO/AIA observations of an extraordinary global extreme ultraviolet (EUV) wave triggered by the X8.2 flare-CME eruption on 2017 September 10. This was one of the best EUV waves ever observed with modern instruments, yet likely the last one of such magnitudes of Solar Cycle 24 as the Sun heads toward the minimum. Its remarkable characteristics include: (1) The wave was observed, for the first time, to traverse the full-Sun corona over the entire visible solar disk and off-limb circumference, manifesting a truly global nature, owing to its exceptionally large amplitude, e.g., with EUV enhancements by up to 300% at 1.1 Rsun from the eruption. (2) This leads to strong transmissions (besides commonly observed reflections) in and out of both polar coronal holes, which are usually ... [READ MORE]
Authors: Wei Liu, Meng Jin, Cooper Downs, Leon Ofman, Mark Cheung, and Nariaki V. Nitta
Projects: SDO-AIA
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Publication Status: Accepted by ApJ Letters (as of July 24, 2018)
Last Modified: 2018-07-29 21:13
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A benchmark study for CHIANTI based on RESIK solar flare spectra
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Cristina Chifor Submitted: 2006-12-04 03:19
Aims. To perform a benchmark analysis for the recent version of the CHIANTI atomic database (v.5.2) based on high-resolution solar flare X-ray spectra in the range 3.4 - 6.1Å from the RESIK crystal spectrometer on the CORONAS-F spacecraft. Methods. A C5.8 flare occurring on 2003 February 22 was chosen for analysis. RESIK spectra of this flare include emission lines of He-like and H-like K,Ar, S, and Si, with some dielectronic lines. Initially, two independent plasma diagnostic techniques are employed: an emission measure (EM) loci analysis using the line fluxand the line contribution function G(T_e, N_e), and a new method based on continuum fluxes and contribution functions. We further apply a differential emission measure (DEM)analysis, from which CHIANTI synthetic spectra ... [READ MORE]
Authors: C. Chifor, G. Del. Zanna, H. E. Mason, J. Sylwester, B. Sylwester, K. J. H. Phillips
Projects: CORONAS-F/SPIRIT
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Publication Status: in press (A&A)
Last Modified: 2006-12-04 10:41
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Publication Status: ApJ, in press for April 20, 2013 issue, arXiv:1303.0563
Last Modified: 2013-03-06 08:54
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Publication Status: Accepted in ApJ
Last Modified: 2012-10-26 14:55
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Publication Status: A&A (accepted)
Last Modified: 2013-08-22 14:49
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Why torus-unstable solar filaments experience failed eruption?
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zhenjun zhou Submitted: 2019-05-01 20:17
To investigate the factors that control the success and/or failure of solar eruptions, we study the magnetic field and 3-Dimensional (3D) configuration of 16 filament eruptions during 2010 July - 2013 February. All these events, i.e., erupted but failed to be ejected to become a coronal mass ejection (CME), are failed eruptions with the filament maximum height exceeding 100Mm. The magnetic field of filament source regions is approximated by a potential field extrapolation method. The filament 3D configuration is reconstructed from three vantage points by the observations of STEREO Ahead/Behind and SDO spacecraft. We calculate the decay index at the apex of these failed filaments and find that in 7 cases, their apex decay indexes exceed the theoretical threshold (ncrit=1.5) of the torus ... [READ MORE]
Authors: Zhenjun Zhou, Xin Cheng, Jie Zhang, Yuming Wang, Dong Wang, Lijuan Liu, Bin Zhuang, Jun Cui
Projects: SDO-AIA,SDO-HMI,STEREO
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Publication Status: under review
Last Modified: 2019-05-03 16:05
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How Many CMEs Have Flux Ropes? Deciphering the Signatures of Shocks, Flux Ropes, and Prominences in Coronagraph Observations of CMEs
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Angelos Vourlidas Submitted: 2012-07-05 15:46
We intend to provide a comprehensive answer to the question on whether all Coronal Mass Ejections (CMEs) have flux rope structure. To achieve this, we present a synthesis of the LASCO CME observations over the last sixteen years, assisted by 3D MHD simulations of the breakout model, EUV and coronagraphic observations from extsl{STEREO} and extsl{SDO}, and statistics from a revised LASCO CME database. We argue that the bright loop often seen as the CME leading edge is the result of pileup at the boundary of the erupting flux rope irrespective of whether a cavity or, more generally, a 3-part CME can be identified. Based on our previous work on white light shock detection and supported by the MHD simulations, we identify a new type of morphology, the `two-front' morphology. It consists of ... [READ MORE]
Authors: A. Vourlidas, B.J. Lynch, R.A. Howard, Y. Li
Projects: SoHO-LASCO,STEREO
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Publication Status: to be published in Solar Physics
Last Modified: 2012-07-07 14:50
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Publication Status: Accepted in ApJL
Last Modified: 2013-10-30 16:59
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Diffraction, Refraction, and Reflection of An Extreme-Ultraviolet Wave Observed during Its Interactions with Remote Active Regions
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Yuandeng Shen Submitted: 2013-07-31 19:06
We present observations of the diffraction, refraction, and reflection of a global extreme-ultraviolet (EUV) wave propagating in the solar corona. These intriguing phenomena are observed when the wave interacts with two remote active regions, and they together exhibit the wave property of this EUV wave. When the wave approached AR11465, it became weaker and finally disappeared in the active region, but a few minutes latter a new wavefront appeared behind the active region, and it was not concentric with the incoming wave. In addition, a reflected wave was also observed simultaneously on the wave incoming side. When the wave approached AR11459, it transmitted through the active region directly and without reflection. The formation of the new wavefront and the transmission could be ... [READ MORE]
Authors: Shen, Yuandeng; Liu, Yu; Su, Jiangtao; Li, Hui; Zhao, Ruijuan; Tian, Zhanjun; Ichimoto, Kiyoshi; Shibata, Kazunari
Projects: SDO-AIA
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Publication Status: accepted by APJ letters
Last Modified: 2013-08-01 11:16
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Publication Status: ApJ, accepted
Last Modified: 2014-05-26 13:03
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Microwave observations of a large-scale coronal wave with the Nobeyama radioheliograph
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Alexander Warmuth Submitted: 2016-10-13 01:08
Context. Large-scale globally propagating waves in the solar corona have been studied extensively, mainly using extreme ultraviolet (EUV) observations. In a few events, corresponding wave signatures have been detected in microwave radioheliograms provided by the Nobeyama radioheliograph (NoRH). Several aspects of these observations seem to contradict the conclusions drawn from EUV observations.
Aims. We investigate whether the microwave observations of global waves are consistent with previous findings.
Methods. We revisited the wave of 1997 Sep 24, which is still the best-defined event in microwaves. We obtained radioheliograms at 17 and 34~GHz from NoRH and studied the morphology, kinematics, perturbation profile evolution, and emission mechanism of the propagating microwave ... [READ MORE]
Authors: Warmuth, A., Shibasaki, K., Iwai, K., & Mann, G.
Projects: Nobeyama Radioheliograph,SoHO-EIT
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Publication Status: Astronomy & Astrophysics (2016), Volume 593, id. A102, 8 pp.
Last Modified: 2016-10-14 09:18
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Publication Status: Published in Astrophys. J. Lett., v683, L207
Last Modified: 2008-11-01 10:03
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Scaling Relations in Coronal Mass Ejections and Energetic Proton Events associated with Solar Superflares
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Takuya Takahashi Submitted: 2016-11-20 22:19
In order to discuss the potential impact of solar 'superflares' on space weather, we investigated statistical relations among energetic proton peak flux with energy higher than $ 10 \rm MeV$ ($F_p$), CME speed
near the Sun ($V_{CME}$) obtained by {\it SOHO}/LASCO coronagraph and flare soft X-ray peak flux in 1-8\AA band ($F_{SXR}$) during 110 major solar proton events (SPEs) recorded from 1996 to 2014. The linear regression fit results in the scaling relations $V_{CME} \propto F_{SXR}^\alpha$, $F_p\propto F_{SXR}^?\eta$ and $F_p\propto V_{CME}^\gamma$ with $\alpha = 0.30\pm 0.04$, $\beta = 1.19 \pm 0.08$ and $\gamma = 4.35 \pm 0.50$, respectively. On the basis of simple physical assumptions, on the other hand, we derive scaling relations expressing CME mass ($M_{CME}$), CME speed and ... [READ MORE]
Authors: Takuya Takahashi, Yoshiyuki Mizuno, Kazunari Shibata
Projects: SoHO-LASCO
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Publication Status: Accepted for publication in ApjL
Last Modified: 2016-11-21 12:29
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Publication Status: ApJ, subm. May 2007
Last Modified: 2007-06-06 15:47
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Publication Status: ApJ in press
Last Modified: 2014-11-19 09:21
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The transition from eruptive to confined flares in the same active region
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Francesco Zuccarello Submitted: 2017-02-13 03:25
Solar flares are sudden and violent releases of magnetic energy in the solar atmosphere that can be divided in eruptive flares, when plasma is ejected from the solar atmosphere, resulting in a coronal mass ejection (CME), and confined flares when no CME is associated with the flare. We present a case-study showing the evolution of key topological structures, such as spines and fans which may determine the eruptive versus non-eruptive behavior of the series of eruptive flares, followed by confined flares, which are all originating from the same site. To study the connectivity of the different flux domains and their evolution, we compute a potential magnetic field model of the active region. Quasi-separatrix layers are retrieved from the magnetic field extrapolation. The change of behavior ... [READ MORE]
Authors: Zuccarello, Francesco P.; Chandra, Ramesh; Schmieder, Brigitte; Aulanier, Guillaume; Joshi, Reetika
Projects: SDO-AIA,SDO-HMI,SoHO-LASCO
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Publication Status: Accepted for publication in Astronomy and Astrophysics
Last Modified: 2017-02-13 12:05
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CORONAL MAGNETIC FIELD MEASUREMENT FROM EUV IMAGES MADE BY THE SOLAR DYNAMICS OBSERVATORY
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Nat Gopalswamy Gopalswamy Submitted: 2013-01-05 05:19
By measuring the geometrical properties of the coronal mass ejection (CME) flux rope and the leading shock observed on 2010 June 13 by the Solar Dynamics Observatory (SDO) mission's Atmospheric Imaging Assembly (AIA) we determine the Alfv?n speed and the magnetic field strength in the inner corona at a heliocentric distance of ~ 1.4 Rs. The basic measurements are the shock standoff distance (ΔR) ahead of the CME flux rope, the radius of curvature of the flux rope (Rc), and the shock speed. We first derive the Alfv?nic Mach number (M) using the relationship, ΔR/Rc = 0.81[(γ-1)M2 + 2]/[(γ+1)(M2-1)], where γ is the only parameter that needed to be assumed. For γ =4/3, the Mach number declined from 3.7 to 1.5 indicating shock weakening within the field of view of ... [READ MORE]
Authors: Nat Gopalswamy, Nariaki Nitta, Sachiko Akiyama, Pertti Makela, and Seiji Yashiro
Projects: SDO-AIA,SoHO-LASCO
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Publication Status: The Astrophysical Journal, 744, 72, 2012
Last Modified: 2013-01-07 12:46
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Solar Sources of 3He-rich Solar Energetic Particle Events in Solar Cycle 24
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Nariaki Nitta Submitted: 2015-05-26 22:40
Using high-cadence extreme-ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we investigate the solar sources of 26 3He-rich solar energetic particle (SEP) events at ≲1 MeV nucleon−1 that were well-observed by the Advanced Composition Explorer during solar cycle 24. Identification of the solar sources is based on the association of 3He-rich events with type III radio bursts and electron events as observed by Wind. The source locations are further verified in EUV images from the Solar and Terrestrial Relations Observatory, which provides information on solar activities in the regions not visible from the Earth. Based on AIA observations, 3He-rich events are not only associated with coronal jets as emphasized in ... [READ MORE]
Authors: Nariaki V. Nitta, Glenn M. Mason, Linghua Wang, Christina M. S. Cohen, Mark E. Wiedenbeck
Projects: ACE,SDO-AIA,SoHO-LASCO,STEREO,Wind
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Publication Status: Published by the Astrophysical Journal
Last Modified: 2015-06-29 11:56
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Publication Status: Space Science Reviews; and Space Science Series of ISSI, Proc. of ISSI Workshop - Solar Dynamics and its Effects on the Heliosph
Last Modified: 2005-07-20 17:54
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Publication Status: A&A (accepted)
Last Modified: 2007-08-16 08:36
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Theoretical Modeling for the STEREO Mission
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Markus J. Aschwanden Submitted: 2005-09-16 16:57
We summarize the theory and modeling efforts for the STEREO mission,
designed for data analysis of both the remote-sensing (SECCHI, SWAVES)
and in-situ instruments (IMPACT, PLASTIC).
The modeling includes the background plasma in the corona,
heliosphere, and solar wind, but concentrates prominently on the dynamic
phenomena associated with the initiation and propagation of coronal mass
ejections (CMEs). The modeling of the CME initiation includes magnetic
shearing, kink instability, filament eruption, and magnetic reconnection
in the flaring lower corona. The modeling of CME propagation entails
interplanetary shocks, interplanetary particle beams, solar energetic
particles (SEPs), geoeffective connections, and space weather.
Authors: Aschwanden,M.J., S.K.Antiochos, J.W.Cook, R.A.Howard, J.T.Karpen, J.A.Klimchuk, N.R.Sheeley, L.A.Fisk, T.I.Gombosi, N.Lugaz, W.IV.Manchester, I.I.Roussev, T.H.Zurbuchen, L.F.Burlaga, M.L.Kaiser, C.Ng, D.V.Reames, M.J.Reiner, C.J.Farrugia, A.Galvin, M.A.Lee, J.A.Linker, Z.Mikic, P.Riley, D.Alexander, A.W.Sandman, E.DeJong, P.C.Liewer, D.Odstrcil, V.Pizzo, J.Luhmann, B.Inhester, E.Marsch, R.W.Schwenn, S.Solanki, V.M.Vasyliunas, T.Wiegelmann, J.-L.H.Bougeret, M.Maksimovic, J.-L.Steinberg, I.H.Cairns, P.A.Robinson, H.Kunow, R.Wimmer-Schweingruber, P.L.Lamy, A.Llebaria, P.Bochsler, V.Bothmer, K.Kecskemety, J.Kota, and M.Scholer
Projects: Soho-EIT,Soho-MDI,Soho-LASCO,TRACE
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Publication Status: Space Science Reviews, Topical Issue on -The STEREO Instruments and Mission-, (eds. Chris T. Russell and Mike L. Kaiser), submit
Last Modified: 2005-09-16 16:57
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The Spatio-Temporal Evolution of Solar Flare Observed with AIA/SDO: Fractal Diffusion, Sub-Diffusion, or Logistic Growth ?}
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Markus J. Aschwanden Submitted: 2012-08-07 15:05
We explore the spatio-temporal evolution of solar flares by fitting
a radial expansion model $r(t)$ that consists of an exponentially
growing acceleration phase, followed by a deceleration phase that
is parameterized by the generalized diffusion function
$r(t) propto kappa (t-t_1)^{eta/2}$, which
includes the logistic growth limit ($eta=0$), sub-diffusion
($eta = 0-1$), classical diffusion ($eta=1$), super-diffusion
($eta = 1-2$), and the linear expansion limit ($eta=2$).
We analyze all M and X-class flares observed with GOES and AIA/SDO
during the first two years of the SDO mission, amounting to 155 events.
We find that most flares operate in the sub-diffusive regime
($eta=0.53pm0.27$), which we interpret in terms of anisotropic
chain reactions of intermittent magnetic ... [READ MORE]
Authors: Markus J. Aschwanden
Projects: SDO-AIA
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Publication Status: ApJ Vol. 757, p.94 (2012)
Last Modified: 2012-09-11 13:42
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Publication Status: Subm. to ApJ, (June 6, 2007)
Last Modified: 2007-06-07 12:37
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Publication Status: JPCS (in press)
Last Modified: 2016-09-27 15:38
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Publication Status: Accepted by ApJ Letters, Sept 17, 2012
Last Modified: 2012-09-19 19:22
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Non-Stationary Fast-Driven Self-Organized Criticality in Solar Flares
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Markus J Aschwanden Submitted: 2019-09-18 13:40
The original concept of self-organized criticality
(Bak et al.~1987), applied to solar flare statistics
(Lu and Hamilton 1991), assumed a slow-driven and
stationary flaring rate, which warrants time scale
separation (between flare durations and inter-flare
waiting times), it reproduces power-law distributions for
flare peak fluxes and durations, but predicts an
exponential waiting
time distribution. In contrast to these classical
assumptions we observe: (i) multiple energy dissipation
episodes during most flares, (ii) violation of the
principle of time scale separation, (iii) a fast-driven
and non-stationary flaring rate, (iv) a power law
distribution for waiting times $\Delta t$, with a slope
of $\alpha_{\Delta t} \approx 2.0$, as predicted from
the universal reciprocality ... [READ MORE]
Authors: Markus J. Aschwanden
Projects: SDO-AIA
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Publication Status: ApJ (subm)
Last Modified: 2019-09-18 23:40
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Observations of a Quasi-Periodic Fast Propagating Magnetosonic Wave in Multi-Wavelength and Its Interaction with Other Magnetic Structures
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Yuandeng Shen Submitted: 2013-07-31 19:11
We present an observational study of a quasi-periodic fast propagating (QFP) magnetosonic wave on 2012, April 23. The multiple wave trains were observed along an active region open loop system which has a divergence geometry. The wave trains were first observed in 171 A observations at a distance of 150 Mm from the footpoint of the guiding loop system and with a speed of 689 km/s, then they appeared in 193 A observations after their interaction with a perpendicular underlaying loop system on the path, in the meantime, the wave speed decelerated to 343 km/s quickly within a short timescale. The sudden deceleration of the wave trains and their appearance in 193 A observations caused by the interaction are interpreted through geometric effect and the density increase of the guiding loop ... [READ MORE]
Authors: Shen, Yuandeng; Liu, Yu.; Su, Jiangtao.; Li, Hui.; Zhang, Xuefei; Tian, Zhanjun; Zhao, Ruijuan; Elmhamdi, Abouazza
Projects: SDO-AIA
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Publication Status: Accepted by Solar Physics
Last Modified: 2013-08-01 11:16
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The evolution of barbs on a polar crown filament observed by SDO
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Leping Li Submitted: 2012-05-07 01:21
From August 16 to 21, 2010, a northern (~ N60) polar crown filament was observed by Solar Dynamics Observatory (SDO). Employing the six day SDO/AIA data, we identify 69 barbs, and select 58 of them, which appeared away from the western solar limb (≤ W60), as our sample. We systematically investigate the evolution of filament barbs. Three different types of apparent formation of barbs are detected, including (1) the convergence of surrounding moving plasma condensations, comprised 55.2% of our sample, (2) the flows of plasma condensations from the filament, composed 37.9%, and (3) the plasma injections from the neighboring brightening regions, comprised 6.9%. We also find three different ways of barb disappearance, involving: (i) the bi-lateral movements (44.8%), and (ii) the ... [READ MORE]
Authors: Leping Li and Jun Zhang
Projects: SDO-AIA
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Publication Status: Accepted by Sol. Phys., 39 pages, 16 figures
Last Modified: 2012-05-07 13:36
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Publication Status: Astronomy & Astrophysics Letters, in press
Last Modified: 2019-10-23 13:06
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A Database of Flare Ribbon Properties from the Solar Dynamics Observatory. I. Reconnection Flux
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Maria D Kazachenko Submitted: 2017-08-30 12:43
We present a database of 3137 solar flare ribbon events corresponding to every flare of GOES class C1.0 and greater within 45? from the central meridian, from 2010 April until 2016 April, observed by the Solar Dynamics Observatory. For every event in the database, we compare the GOES peak X-ray flux with the corresponding active region and flare ribbon properties. We find that while the peak X-ray flux is not correlated with the active region unsigned magnetic flux, it is strongly correlated with the flare ribbon reconnection flux, flare ribbon area, and the fraction of active region flux that undergoes reconnection. We find the relationship between the peak X-ray flux and the flare ribbon reconnection flux to be I_{X,peak} ~ (Φ_ribbon)^1.5. This scaling law is consistent with ... [READ MORE]
Authors: Kazachenko, Maria D.; Lynch, Benjamin J.; Welsch, Brian T.; Sun, Xudong
Projects: GOES X-rays,SDO-AIA,SDO-HMI
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Publication Status: The Astrophysical Journal, Volume 845, Issue 1, article id. 49, 13 pp. (2017).
Last Modified: 2017-08-30 13:42
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Publication Status: Accepted for publication in The Astrophysical Journal
Last Modified: 2019-05-03 16:05
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Publication Status: ApJ, accepted
Last Modified: 2012-10-15 12:44
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Publication Status: Solar Physics, (in press)
Last Modified: 2010-02-19 13:50
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Publication Status: Submitted to the ApJ
Last Modified: 2017-04-12 17:38
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The large longitudinal spread of solar energetic particles during the January 17, 2010 solar event
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Nina Dresing Submitted: 2012-06-08 02:03
We investigate multi-spacecraft observations of the January 17, 2010 solar energetic particle event. Energetic electrons and protons have been observed over a remarkable large longitudinal range at the two STEREO spacecraft and SOHO suggesting a longitudinal spread of nearly 360 degrees at 1,AU. The flaring active region, which was on the backside of the Sun as seen from Earth, was separated by more than 100 degrees in longitude from the magnetic footpoints of each of the three spacecraft. The event is characterized by strongly delayed energetic particle onsets with respect to the flare and only small or no anisotropies in the intensity measurements at all three locations. The presence of a coronal shock is evidenced by the observation of a type II radio burst from the Earth and ... [READ MORE]
Authors: N. Dresing, R.Gomez-Herrero, A. Klassen, B. Heber, Y. Kartavykh, W. Droege
Projects: ACE,GONG,SoHO-EIT,STEREO
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Publication Status: accepted
Last Modified: 2012-06-28 04:02
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Publication Status: ApJ, accepted
Last Modified: 2015-11-05 11:05
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Publication Status: ApJL, accepted
Last Modified: 2017-09-20 09:05
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Statistical Analysis of Torus and Kink Instabilities in Solar Eruptions
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Ju Jing Submitted: 2018-10-02 09:14
A recent laboratory experiment of ideal magnetohydrodynamic instabilities revealed four distinct eruption regimes readily distinguished by the torus instability (TI) and helical kink instability (KI) parameters. To establish its observational counterpart, we collected 38 solar flares (stronger than GOES-class M5 in general) that took place within 45? of disk center during 2011?2017, 26 of which are associated with a halo or partial halo coronal mass ejection (CME; i.e., ejective events), while the others are CME-less (i.e., confined events). This is a complete sample of solar events satisfying our selection criteria detailed in the paper. For each event, we calculate a decay index n of the potential strapping field above the magnetic flux rope (MFR) in and around the flaring magnetic ... [READ MORE]
Authors: Ju Jing, Chang Liu, Jeongwoo Lee, Hantao Ji, Nian Liu, Yan Xu, and Haimin Wang
Projects: SDO-AIA,SDO-HMI,SoHO-LASCO
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Publication Status: published in ApJ
Last Modified: 2018-10-02 10:55
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Publication Status: The Astrophysical Journal (ApJ)
Last Modified: 2011-10-03 11:11
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Publication Status: Astrophys. J., accepted
Last Modified: 2016-09-10 13:39
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Publication Status: Submitted to Astrophysical Journal Supplement
Last Modified: 2017-11-01 12:23
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Publication Status: ApJ 699, 133 (2009)
Last Modified: 2009-06-29 09:40
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Publication Status: ApJ (Accepted)
Last Modified: 2013-08-19 09:04
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The origin of the modulation of the radio emission from the solar corona by a fast magnetoacoustic wave
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Dmitrii Kolotkov Submitted: 2018-05-21 07:20
Observational detection of quasi-periodic drifting fine structures in a type III radio burst associated with a solar flare SOL2015-04-16T11:22, with Low Frequency Array, is presented. Although similar modulations of the type III emission have been observed before and were associated with the plasma density fluctuations, the origin of those fluctuations was unknown. Analysis of the striae of the intensity variation in the dynamic spectrum allowed us to reveal two quasi-oscillatory components. The shorter component has the apparent wavelength of $\sim2$\,Mm, phase speed of $\sim657$\,km\,s$^{-1}$, which gives the oscillation period of $\sim3$\,s, and the relative amplitude of $\sim0.35$\%. The longer component has the wavelength of $\sim12$\,Mm, and relative amplitude of $\sim5.1$\%. The ... [READ MORE]
Authors: Dmitrii Y. Kolotkov, Valery M. Nakariakov, Eduard P. Kontar
Projects: LOw Frequency ARray (LOFAR)
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Publication Status: accepted for publication in ApJ
Last Modified: 2018-05-21 10:03
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Publication Status: J. Geophysical Research, Vol. 115, A07106, doi:10.1029/2009JA015099
Last Modified: 2010-07-21 17:23
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Trigger of a blowout jet in a solar coronal mass ejection associated with a flare
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Shuhong Yang Submitted: 2015-11-05 19:44
Using the multi-wavelength images and the photospheric magnetograms from the Solar Dynamics Observatory, we study the flare which was associated by the only one coronal mass ejection (CME) in active region (AR) 12192. The eruption of a filament caused a blowout jet, and then an M4.0 class flare occurred. This flare was located at the edge of AR instead of in the core region. The flare was close to the apparently "open" fields, appearing as extreme-ultraviolet structures that fan out rapidly. Due to the interaction between flare materials and "open" fields, the flare became an eruptive flare, leading to the CME. Then at the same site of the first eruption, another small filament erupted. With the high spatial and temporal resolution H? data from the New Vacuum Solar Telescope at the ... [READ MORE]
Authors: Xiaohong Li, Shuhong Yang, Huadong Chen, Ting Li, Jun Zhang
Projects: Other,SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in ApJL
Last Modified: 2015-11-06 10:53
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Publication Status: accepted for publication in MNRAS
Last Modified: 2016-10-03 12:31
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Comparative Study of Microwave Polar Brightening, Coronal Holes, and Solar Wind Over the Solar Poles
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Ken'ichi Fujiki Submitted: 2019-02-28 23:15
We comparatively studied the long-term variation (1992-2017) in polar brightening observed with the Nobeyama Radioheliograph, the polar solar wind velocity with interplanetary scintillation observations at the Institute for Space-Earth Environmental Research, and the coronal hole distribution computed by potential field calculations of the solar corona using synoptic magnetogram data obtained at Kitt Peak National Solar Observatory. First, by comparing the solar wind velocity (V) and the brightness temperature (T_b) in the polar region, we found good correlation coefficients (CCs) between V and T_b in the polar regions, CC = 0.91 (0.83) for the northern (southern) polar region, and we obtained the V-T_b relationship as V =12.6 (T_b-10,667)^{1/2}+432. We also confirmed that the CC of V-T_b ... [READ MORE]
Authors: Ken'ichi Fujiki, Kiyoto Shibasaki, Seiji Yashiro, Munetoshi Tokumaru, Kazumasa Iwai, Satoshi Masuda
Projects: Nobeyama Radioheliograph
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Publication Status: Solar Physics 2019 in press (DOI: 10.1007/s11207-019-1418-6)
Last Modified: 2019-03-05 12:48
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Publication Status: 2015, ApJ, accepted
Last Modified: 2015-05-27 14:14
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Automatic Detection and Tracking of Coronal Mass Ejections II: Multiscale Filtering of Coronagraph Images
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Jason P. Byrne Submitted: 2012-06-13 13:24
Studying coronal mass ejections (CMEs) in coronagraph data can be challenging due to their diffuse structure and transient nature, and user-specific biases may be introduced through visual inspection of the images. The large amount of data available from the Solar and Heliospheric Observatory (SOHO), Solar TErrestrial RElations Observatory (STEREO), and future coronagraph missions also makes manual cataloging of CMEs tedious, and so a robust method of detection and analysis is required. This has led to the development of automated CME detection and cataloging packages such as CACTus, SEEDS, and ARTEMIS. Here, we present the development of a new CORIMP (coronal image processing) CME detection and tracking technique that overcomes many of the drawbacks of current catalogs. It works by first ... [READ MORE]
Authors: Jason P. Byrne, Huw Morgan, Shadia R. Habbal, Peter T. Gallagher
Projects: SoHO-LASCO,STEREO
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Publication Status: Published
Last Modified: 2012-06-08 07:27
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Publication Status: A&A 421, L33-L36 (2004)
Last Modified: 2004-06-27 05:19
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Quasi-Periodic Pulsations in Solar Flares
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Victor Melnikov Submitted: 2009-07-26 06:48
Quasi-periodic pulsations (QPP) are a common feature of flaring energy releases in the solar atmosphere, observed in all bands, from radio to hard X-ray. In this review we concentrate on QPP with the periods longer than one second. Physical mechanisms responsible for the generation of long QPP split into two groups: ?load/unload? mechanisms and MHD oscillations. Load/unload mechanisms are repetitive regimes of flaring energy releases by magnetic reconnection or by other means. MHD oscillations can affect all elements of the flaring emission generation: triggering of reconnection and modulation of its rate, acceleration and dynamics of non-thermal electrons, and physical conditions in the emitting plasmas. In the case of MHD oscillations, the periodicity of QPP is determined either by the ... [READ MORE]
Authors: Nakariakov, V. M. and Melnikov, V. F.
Projects: CORONAS-F/SPIRIT,Hinode/XRT,RHESSI,SoHO-MDI,SoHO-SUMER,TRACE,Yohkoh-HXT
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Publication Status: Space Science Reviews (accepted), Online First
Last Modified: 2009-07-27 10:48
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Eruption of a kink-unstable filament in active region NOAA 10696
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David R. Williams Submitted: 2005-06-23 05:19
We present rapid-cadence Transition Region And Coronal Explorer (TRACE) observations which show evidence of a filament eruption from active region NOAA 10696, accompanied by an X2.5 flare, on 2004 November 10. The eruptive filament, which manifests as a fast coronal mass ejection some minutes later, rises as a kinking structure with an apparently exponential growth of height within TRACE's field of view. We compare the characteristics of this filament eruption with MHD numerical simulations of a kink-unstable magnetic flux rope, finding excellent qualitative agreement. We suggest that, while tether-weakening by breakout-like quadrupolar reconnection may be the release mechanism for the previously confined flux rope, the driver of the expansion is most likely the MHD helical kink ... [READ MORE]
Authors: David R. Williams, Tibor Török, Pascal Démoulin, Lidia van Driel-Gesztelyi, Bernhard Kliem
Projects: Soho-EIT,Soho-MDI,TRACE
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Publication Status: ApJ Letters (accepted)
Last Modified: 2005-06-23 05:19
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Magnetic Kelvin-Helmholtz Instability at the Sun
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Claire Foullon Submitted: 2011-01-21 00:05
Flows and instabilities play a major role in the dynamics of magnetised plasmas including the solar corona, magnetospheric and heliospheric boundaries, cometary tails and astrophysical jets. The non-linear effects, multi-scale and microphysical interactions inherent to the flow-driven instabilities are believed to play a role, e.g., in plasma entry across a discontinuity, generation of turbulence and enhanced drag. However, in order to clarify the efficiency of macroscopic instabilities in these processes, we lack proper knowledge of their overall morphological features. Here we show the first observations of the temporally and spatially resolved evolution of the magnetic Kelvin-Helmholtz instability in the solar corona. Unprecedented high-resolution imaging observations of vortices ... [READ MORE]
Authors: Foullon, C., Verwichte, E., Nakariakov, V.M., Nykyri, K. and Farrugia, C.J.
Projects: SDO-AIA
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Publication Status: ApJL, accepted (20-01-2011)
Last Modified: 2011-01-21 08:46
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Publication Status: Solar Physics (in press)
Last Modified: 2005-12-02 12:46
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Publication Status: submitted
Last Modified: 2009-04-11 09:44
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Turbulence, Complexity, and Solar Flares
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R.T.James McAteer Submitted: 2009-09-30 09:42
The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need for accurate space weather forecasts. Solar flares arise naturally as a competition between an input (flux emergence and rearrangement) in the photosphere and an output (electrical current build up and resistive dissipation) in the corona. Although initially localised, this redistribution affects neighbouring regions and an avalanche occurs resulting in large scale eruptions of plasma, particles, and magnetic field. As flares are powered from the stressed field rooted in the photosphere, a study of the photospheric magnetic complexity can be used to both ... [READ MORE]
Authors: R. T. James McAteer, Peter T. Gallagher, Paul A. Conlon
Projects: GONG,Mount Wilson Observatory,SoHO-MDI
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Publication Status: Advances in Space Science Research
Last Modified: 2009-10-01 06:31
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Measurement of Vector Magnetic Field in a Flare kernel with a Spectropolarimetric Observation in He I 10830 A
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Tetsu Anan Submitted: 2018-08-27 15:03
A flare kernel associated with a C4 class flare was observed in a spectral window including the He I triplet 10830 A and Si I 10827 A with a spectropolarimeter on the Domeless Solar Telescope at Hida Observatory on August 9th, 2015. Observed Stokes profiles of the He I triplet in the flare kernel in its post-maximum phase are well reproduced through inversions considering the Zeeman and the Paschen-Back effects with a three slab model of the flare kernel, in which two slabs having up and downward velocities produce emissions and one slab produces an absorption. The magnetic field strength inferred from the emission components of the He I line is 1400 G, which is significantly stronger than 690 G that is observed at the same location in the same line 6.5 hours before the flare. In ... [READ MORE]
Authors: Tetsu Anan, Takurou Yoneya, Kiyoshi Ichimoto, Satoru Ueno, Daikou Shiota, Satoshi Nozawa, Shinsuke Takasao, Tomoko Kawate
Projects: Domeless Solar Telescope (Hida Observatory)
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Publication Status: accepted for publication in PASJ
Last Modified: 2018-08-31 12:55
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Publication Status: A&A (accepted)
Last Modified: 2010-04-07 13:37
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Publication Status: Acceped, Solar Physics
Last Modified: 2019-11-06 10:37
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High-Cadence and High-Resolution Halpha Imaging Spectroscopy of a Circular Flare's Remote Ribbon with IBIS
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Na Deng Submitted: 2013-04-16 07:46
We present an unprecedented high-resolution ha imaging spectroscopic observation of a C4.1 flare taken with the Interferometric Bidimensional Spectrometer (IBIS) in conjunction with the adaptive optics system at the 76~cm Dunn Solar Telescope on 2011 October 22 in active region NOAA 11324. Such a two-dimensional spectroscopic observation covering the entire evolution of a flare ribbon with high spatial (0.1arcpix image scale), cadence (4.8~s) and spectral (0.1~AA stepsize) resolution is rarely reported. The flare consists of a main circular ribbon that occurred in a parasitic magnetic configuration and a remote ribbon that was observed by the IBIS. Such a circular-ribbon flare with a remote brightening is predicted in 3D fan-spine reconnection but so far has been rarely ... [READ MORE]
Authors: Na Deng, Alexandra Tritschler, Ju Jing, Xin Chen, Chang Liu, Kevin Reardon, Carsten Denker, Yan Xu, and Haimin Wang
Projects: Hinode/SOT,National Solar Observatory (Sac Peak),RHESSI,SDO-AIA,SDO-HMI
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Publication Status: The Astrophysical Journal, accepted
Last Modified: 2013-04-17 12:22
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Publication Status: ApJS in press
Last Modified: 2016-03-08 12:17
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Publication Status: Accepted by A&A
Last Modified: 2015-09-16 13:50
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Modeling of the sunspot-associated microwave emission using a new method of DEM inversion
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Costas Alissandrakis Submitted: 2018-12-17 08:24
We developed a method to compute the temperature and density structure along the line of sight by inversion of the differential emission measure (DEM), under the assumptions of stratification and hydrostatic equilibrium. We applied this method to the DEM obtained from AIA observations and used the results, together with potential extrapolations of the photospheric magnetic field, to compute the microwave emission of three sunspots, which we compared with observations from the RATAN-600 radio telescope and the Nobeyama Radioheliograph (NoRH). Our DEM based models reproduced very well the observations of the moderate-size spot on October 2011 and within 25% the data of a similar sized spot on March 2016, but predicted too low values for the big spot of April 14, 2016. The latter was better ... [READ MORE]
Authors: C. E. Alissandrakis, V. M. Bogod, T. I. Kaltman, S. Patsourakos, N. G. Peterova
Projects: Nobeyama Radioheliograph,RATAN-600,SDO-AIA
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Publication Status: Acceped for publication in Solar Physics
Last Modified: 2018-12-19 12:30
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Quasi-periodic pulsations with varying period in multi-wavelength observations of an x-class flare
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Jing Huang Submitted: 2014-08-03 20:53
This work presents an interesting phenomenon of the period variation in quasi-periodic pulsations (QPPs) observed during the impulsive phase of a coronal mass ejection-related X1.1 class flare on 2012 July 6. The period of QPPs
was changed from 21 s at soft X-rays (SXR) to 22?23 s at microwaves, to ∼24 s at extreme ultraviolet emissions
(EUV), and to 27?32 s at metric?decimetric waves. The microwave, EUV and SXR QPPs, emitted from flare loops
of different heights, were oscillating in phase. Fast kink mode oscillations were proposed to be the modulation
mechanism, which may exist in a wide region in the solar atmosphere from the chromosphere to the upper corona
or even to the interplanetary space. Changed parameters of flare loops through the solar atmosphere could result
in ... [READ MORE]
Authors: Jing Huang, Baolin Tan, Yin Zhang, Marian Karlick?y, and Hana M?esz?arosov?a
Projects: GOES X-rays ,SDO-AIA,SDO-HMI
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Publication Status: published
Last Modified: 2014-08-04 17:58
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Flare Footpoint Regions and a Surge Observed by the Hinode/EUV Imaging Spectrometer (EIS), RHESSI, and SDO/AIA
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Amir Caspi Submitted: 2015-10-28 16:05
The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft observed flare footpoint regions coincident with a surge for a M3.7 flare observed on 25 September 2011 at N12 E33 in active region 11302. The flare was observed in spectral lines of O VI, Fe X, Fe XII, Fe XIV, Fe XV, Fe XVI, Fe XVII, Fe XXIII and Fe XXIV. The EIS observations were made coincident with hard X-ray bursts observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Overlays of the RHESSI images on the EIS raster images at different wavelengths show a spatial coincidence of features in the RHESSI images with the EIS upflow and downflow regions, as well as loop-top or near-loop-top regions. A complex array of phenomena was observed including multiple evaporation regions and the ... [READ MORE]
Authors: George A. Doschek, Harry P. Warren, Brian R. Dennis, Jeffrey W. Reep, Amir Caspi
Projects: Hinode/EIS,RHESSI,SDO-AIA
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Publication Status: Published -- Doschek, G. A., Warren, H. P., Dennis, B. R., Reep, J. W., & Caspi, A. 2015, ApJ, 813, 32; DOI 10.1088/0004-637X/813/1/32
Last Modified: 2015-11-02 10:52
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Predicting Coronal Mass Ejections Using Machine Learning Methods
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Monica Bobra Submitted: 2016-03-23 12:26
Of all the activity observed on the Sun, two of the most energetic events are flares and Coronal Mass Ejections (CMEs). Usually, solar active regions that produce large flares will also produce a CME, but this is not always true (Yashiro et al., 2005). Despite advances in numerical modeling, it is still unclear which circumstances will produce a CME (Webb & Howard, 2012). Therefore, it is worthwhile to empirically determine which features distinguish flares associated with CMEs from flares that are not. At this time, no extensive study has used physically meaningful features of active regions to distinguish between these two populations. As such, we attempt to do so by using features derived from [1] photospheric vector magnetic field data taken by the Solar Dynamics Observatory's ... [READ MORE]
Authors: Monica G. Bobra and Stathis Ilondis
Projects: GOES X-rays ,SDO-HMI,STEREO
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Publication Status: Accepted for publication in the Astrophysical Journal
Last Modified: 2016-03-30 20:57
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Reconstruction of a Large-scale Pre-flare Coronal Current Sheet Associated with an Homologous X-shaped Flare
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Chaowei Jiang Submitted: 2017-10-10 19:32
As a fundamental magnetic structure in the solar corona, electric current sheets (CSs) can form either prior to or during solar flare, and they are essential for magnetic energy dissipation in the solar corona by enabling magnetic reconnection. However static reconstruction of CS is rare, possibly due to limitation inherent in available coronal field extrapolation codes. Here we present the reconstruction of a large-scale pre-flare CS in solar active region 11967 using an MHD-relaxation model constrained by SDO/HMI vector magnetogram. The CS is found to be associated with a set of peculiar homologous flares that exhibit unique X-shaped ribbons and loops occurring in a quadrupolar magnetic configuration. This is evidenced by that the field lines traced from the CS to the photosphere form ... [READ MORE]
Authors: Chaowei Jiang, Xiaoli Yan, Xueshang Feng, Aiying Duan, Qiang Hu, Pingbing Zuo, Yi Wang
Projects: SDO-AIA,SDO-HMI
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Publication Status: Accepted by ApJ
Last Modified: 2017-10-11 06:20
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Companion Event and Precursor of the X17 Flare on 28 October, 2003
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Cristina H. Mandrini Submitted: 2006-08-31 05:27
A major two-ribbon X17 flare occurred on 28 October, 2003, starting at 11:01 UT in active region NOAA 10486. This flare was accompanied by the eruption of a filament and by one of the fastest halo coronal mass ejections registered during the October-November 2003 strong activity
period.
We focus on the analysis of magnetic field (SoHO/MDI),
chromospheric (NainiTal Observatory and TRACE) and coronal (TRACE) data obtained before and during the 28 October event. By combining our data analysis with a model of the coronal magnetic field, we concentrate on the study of
two events starting before the main flare.
One of these events, evident in TRACE images around one hour prior to the main flare, involves a localized magnetic reconnection process associated with the presence of a coronal ... [READ MORE]
Authors: Mandrini, C.H., Demoulin, P., Schmieder, B., DeLuca, E.E., Pariat, E., Uddin, W.
Projects: SoHO-MDI,TRACE
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Publication Status: Solar Phys. (in press)
Last Modified: 2006-08-31 10:17
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Publication Status: accepted to Solar Physics
Last Modified: 2016-05-04 09:22
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First Detection of Solar Flare Emission in Middle-Ultraviolet Balmer Continuum
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Marie Dominique Submitted: 2018-10-24 01:59
We present the first detection of solar flare emission at middle-ultraviolet wavelengths around 2000 A by the channel 2 of the Large-Yield RAdiometer (LYRA) onboard the PROBA2 mission. The flare (SOL20170906) was also observed in the channel 1 of LYRA centered at the H I Lyman-α line at 1216 A, showing a clear non-thermal profile in both channels. The flare radiation in channel 2 is consistent with the hydrogen Balmer continuum emission produced by an optically thin chromospheric slab heated up to 10000 K. Simultaneous observations in channels 1 and 2 allow the separation of the line emission (primarily from the Lyman-α line) from the Balmer continuum emission. Together with the recent detection of the Balmer continuum emission in the near-ultraviolet by IRIS, the LYRA ... [READ MORE]
Authors: Marie Dominique, Andrei N. Zhukov, Petr Heinzel, Ingolf E. Dammasch, Laurence Wauters, Laurent Dolla, Sergei Shestov, Matthieu Kretzschmar, Janet Machol, Giovanni Lapenta, Werner Schmutz
Projects: PROBA2/LYRA
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Publication Status: Accepted in ApJL
Last Modified: 2018-10-24 10:42
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Publication Status: In Solar and Stellar Variability: Impact on Earth and Planets, Proceedings IAU Symposium No. 264, 2009, H. Andrei, A. Kosovichev & J.-P. Rozelot, eds. (in press)
Last Modified: 2010-01-16 07:28
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February 15, 2011: sun-quakes produced by flux rope eruption
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Sergei Zharkov Submitted: 2011-10-11 23:09
We present an analysis of the 2011 February 15 X-class solar flare, previously reported to produce the first sunquake in solar cycle 24. Using acoustic holography, we confirm the first, and report a second, weaker, seismic source associated with this flare. We find that the two sources are located at either end of a sigmoid, which indicates the presence of a flux rope. Contrary to the majority of previously reported sunquakes, the acoustic emission precedes the peak of major hard X-ray (HXR) sources by several minutes. Furthermore, the strongest HXR footpoints derived from RHESSI data are found to be located away from the seismic sources in the flare ribbons. We account for these discrepancies within the context of a phenomenological model of a flux rope eruption and accompanying ... [READ MORE]
Authors: Zharkov, S.I., Green, L.M., Matthews, S.A and Zharkova, V.V.
Projects: SDO-AIA,SDO-HMI
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Publication Status: Astrophysical Journal Letters, in press
Last Modified: 2011-10-12 09:18
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Publication Status: Accepted
Last Modified: 2010-07-06 10:28
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Publication Status: In press for Astrophysical Journal
Last Modified: 2009-12-07 10:36
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On-disc Observations of Flux Rope Formation Prior to its Eruption
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Alexander James Submitted: 2017-04-11 07:46
Coronal mass ejections (CMEs) are one of the primary manifestations of solar activity and can drive severe space weather effects. Therefore, it is vital to work towards being able to predict their occurrence. However, many aspects of CME formation and eruption remain unclear, including whether magnetic flux ropes are present before the onset of eruption and the key mechanisms that cause CMEs to occur. In this work, the pre-eruptive coronal configuration of an active region that produced an interplanetary CME with a clear magnetic flux rope structure at 1 AU is studied. A forward-S sigmoid appears in extreme-ultraviolet (EUV) data two hours before the onset of the eruption (SOL2012-06-14), which is interpreted as a signature of a right-handed flux rope that formed prior to the eruption. ... [READ MORE]
Authors: A. W. James, L. M. Green, E. Palmerio, G. Valori, H. A. S. Reid, D. Baker, D. H. Brooks, L. van Driel-Gesztelyi, E. K. J. Kilpua
Projects: GOES X-rays,Hinode/EIS,Nan?ay Radioheliograph,SDO-AIA,SDO-HMI
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Publication Status: Accepted
Last Modified: 2017-04-11 23:28
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Coronal Shock Waves, EUV waves, and Their Relation to CMEs. I. Reconciliation of ''EIT waves'', Type II Radio Bursts, and Leading Edges of CMEs
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Victor Grechnev Submitted: 2011-04-18 19:49
We show examples of excitation of coronal waves by flare-related abrupt eruptions of magnetic rope structures. The waves presumably rapidly steepened into shocks and freely propagated afterwards like decelerating blast waves that showed up as Moreton waves and EUV waves. We propose a simple quantitative description for such shock waves to reconcile their observed propagation with drift rates of metric type II bursts and kinematics of leading edges of coronal mass ejections (CMEs). Taking account of different plasma density falloffs for propagation of a wave up and along the solar surface, we demonstrate a close correspondence between drift rates of type II bursts and speeds of EUV waves, Moreton waves, and CMEs observed in a few known events.
Authors: V. V. Grechnev, A. M. Uralov, I. M. Chertok, I. V. Kuzmenko, A. N. Afanasyev, N. S. Meshalkina, S. S. Kalashnikov, Y. Kubo
Projects: TRACE
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Publication Status: Accepted for publication in Solar Physics
Last Modified: 2011-04-19 06:30
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Solar Cycle Variation of Magnetic Flux Ropes in a Quasi-Static Coronal Evolution Model
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Anthony Yeates Submitted: 2010-03-25 04:35
The structure of electric current and magnetic helicity in the solar corona is closely linked to solar activity over the 11-year cycle, yet is poorly understood. As an alternative to traditional current-free ''potential field'' extrapolations, we investigate a model for the global coronal magnetic field which is non-potential and time-dependent, following the build-up and transport of magnetic helicity due to flux emergence and large-scale photospheric motions. This helicity concentrates into twisted magnetic flux ropes, which may lose equilibrium and be ejected. Here, we consider how the magnetic structure predicted by this model-in particular the flux ropes-varies over the solar activity cycle, based on photospheric input data from six periods of cycle 23. The number of flux ropes ... [READ MORE]
Authors: Yeates, A.R., Constable, J.A., and Martens, P.C.H.
Projects: SoHO-LASCO
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Publication Status: Solar Physics (in press)
Last Modified: 2010-03-25 08:29
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An Updated View of Solar Eruptive Flares and Development of Shocks and CMEs: History of the 2006 December 13 GLE-Productive Extreme Event
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Victor Grechnev Submitted: 2013-08-13 21:20
An extreme 2006 December 13 event marked the onset of the Hinode era being the last major flare in the solar cycle 23 observed with NoRH and NoRP. The event produced a fast CME, strong shock, and big particle event responsible for GLE70. We endeavor to clarify relations between eruptions, shock wave, and the flare, and to shed light on a debate over the origin of energetic protons. One concept relates it with flare processes. Another one associates acceleration of ions with a bow shock driven by a CME at (2-4)R_sun. The latter scenario is favored by a delayed particle release time after the flare. However, our previous studies have established that a shock wave is typically excited by an impulsively erupting magnetic rope (future CME core) during the flare rise, while the outer CME ... [READ MORE]
Authors: V. Grechnev, V. Kiselev, A. Uralov, N. Meshalkina, A. Kochanov
Projects: GOES X-rays ,Hinode/SOT,Hinode/XRT,Nobeyama Radioheliograph,RHESSI,SoHO-EIT,SoHO-MDI,SoHO-LASCO,SXI
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Publication Status: Accepted for publication in PASJ
Last Modified: 2013-08-14 08:28
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AIA Multithermal Loop Analysis: First Results
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Joan Schmelz Submitted: 2011-02-14 09:44
The Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory has state-of-the-art spatial resolution and shows the most detailed images of coronal loops ever observed. The series of coronal filters peak at different temperatures, which span the range of active regions. These features represent a significant improvement over earlier coronal imagers and make AIA ideal for multi-thermal analysis. Here we targeted a 171Å coronal loop in AR 11092 observed by AIA on 2010 August 3. Isothermal analysis using the 171-to-193 ratio gave a temperature of Log T ∼ 6.1, similar to the results of EIT and TRACE. Differential Emission Measure analysis, however, showed that the plasma was multithermal, not isothermal, with the bulk of the emission measure at Log T > 6.1. The result ... [READ MORE]
Authors: Schmelz, Kimble, Jenkins, Worley, Anderson, Pathak, Saar
Projects: SDO-AIA
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Publication Status: ApJ Letters, 725, L34, 2010
Last Modified: 2011-02-14 11:04
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Publication Status: Accepted for publication in ApJ.
Last Modified: 2016-09-21 11:19
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Hinode/EIS Spectroscopic Validation of Very Hot Plasma Imaged with the Solar Dynamics Observatory in Non-flaring Active Region Cores
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Fabio Reale Submitted: 2012-04-27 08:52
We use coronal imaging observations with the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA), and Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS) spectral data to explore the potential of narrowband EUV imaging data for diagnosing the presence of hot (T >~ 5 MK) coronal plasma in active regions. We analyze observations of two active regions (AR 11281, AR 11289) with simultaneous AIA imaging and EIS spectral data, including the Ca XVII line (at 192.8 A), which is one of the few lines in the EIS spectral bands sensitive to hot coronal plasma even outside flares. After careful co-alignment of the imaging and spectral data, we compare the morphology in a three-color image combining the 171, 335, and 94 A AIA spectral bands, with the image obtained for Ca XVII emission from ... [READ MORE]
Authors: Testa, P., Reale, F.
Projects: Hinode/EIS,SDO-AIA
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Publication Status: ApJ Letters, 2012, 750, L10
Last Modified: 2012-04-27 09:07
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Microflare Heating of a Solar Active Region Observed with NuSTAR, Hinode/XRT, and SDO/AIA
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Paul Wright Submitted: 2017-07-21 08:11
NuSTAR is a highly sensitive focusing hard X-ray (HXR) telescope and has observed several small microflares in its initial solar pointings. In this paper, we present the first joint observation of a microflare with NuSTAR and Hinode/XRT on 2015 April 29 at ~11:29 UT. This microflare shows heating of material to several million Kelvin, observed in Soft X-rays (SXRs) with Hinode/XRT, and was faintly visible in Extreme Ultraviolet (EUV) with SDO/AIA. For three of the four NuSTAR observations of this region (pre-, decay, and post phases) the spectrum is well fitted by a single thermal model of 3.2-3.5 MK, but the spectrum during the impulsive phase shows additional emission up to 10 MK, emission equivalent to A0.1 GOES class. We recover the differential emission measure (DEM) using SDO/AIA, ... [READ MORE]
Authors: Paul J. Wright, Iain G. Hannah, Brian W. Grefenstette, Lindsay Glesener, S?m Krucker, Hugh S. Hudson, David M. Smith, Andrew J. Marsh, Stephen M. White, Matej Kuhar
Projects: GOES X-rays,Hinode/XRT,NuSTAR,SDO-AIA
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Publication Status: ApJ (accepted)
Last Modified: 2017-07-21 21:31
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Changes in quasi-periodic variations of solar photospheric fields: precursor to the deep solar minimum in the cycle 23?
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Susanta Kumar Bisoi Submitted: 2013-05-06 01:41
Using both wavelet and Fourier analysis, a study has been undertaken of the changes in the quasi-periodic variations in solar photospheric fields in the build-up to one of the deepest solar minima experienced in the past 100 years. This unusual and deep solar minimum occurred between solar cycles 23 and 24. The study, carried out using ground based synoptic magnetograms spanning the period 1975.14 to 2009.86, covered solar cycles 21, 22 and 23. A hemispheric asymmetry in periodicities of the photospheric fields was seen only at latitudes above 45 degree when the data was divided, based on a wavelet analysis, into two parts: one prior to 1996 and the other after 1996. Furthermore, the hemispheric asymmetry was observed to be confined to the latitude range 45 degree to 60 degree. This ... [READ MORE]
Authors: Susanta Kumar Bisoi, P. Janardhan, D. Chakrabarty, S. Ananthakrishnan, and Ankur Divekar
Projects: National Solar Observatory (Sac Peak)
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Publication Status: Solar Physics (accepted for publication)
Last Modified: 2013-05-06 11:08
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The First Ground Level Enhancement Event of Solar Cycle 24: Direct Observation of Shock Formation and Particle Release Heights
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Nat Gopalswamy Submitted: 2013-02-07 00:09
We report on the 2012 May 17 Ground Level Enhancement (GLE) event, which is the first of its kind in Solar Cycle 24. This is the first GLE event to be fully observed close to the surface by the Solar Terrestrial Relations Observatory (STEREO) mission. We determine the coronal mass ejection (CME) height at the start of the associated metric type II radio burst (i.e., shock formation height) as 1.38 Rs (from the Sun center). The CME height at the time of GLE particle release was directly measured from a STEREO image as 2.32 Rs, which agrees well with the estimation from CME kinematics. These heights are consistent with those obtained for cycle-23 GLEs using back-extrapolation. By contrasting the 2012 May 17 GLE with six other non-GLE eruptions from well-connected regions with similar or ... [READ MORE]
Authors: N. Gopalswamy, H. Xie, S. Akiyama, S. Yashiro, I. G. Usoskin, and J. M. Davila
Projects: GOES X-rays ,Neutron Monitors,SDO-AIA,SoHO-LASCO,STEREO
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Publication Status: Accepted for publication, ApJL, February 6, 2013
Last Modified: 2013-02-07 00:09
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The Properties of Solar Energetic Particle Event-Associated Coronal Mass Ejections Reported in Different CME Catalogs
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Ian Richardson Submitted: 2015-05-13 09:56
We compare estimates of the speed and width of coronal mass ejections (CMEs) in several catalogs for the CMEs associated with ~200 solar energetic particle (SEP) events in 2006-2013 that included 25 MeV protons. The catalogs used are: CDAW, CACTUS, SEEDS and CORIMP, all derived from observations by the LASCO coronagraphs on the SOHO spacecraft, the CACTUS catalog derived from the COR2 coronagraphs on the STEREO-A and -B spacecraft, and the DONKI catalog, which uses observations from SOHO and the STEREO spacecraft. We illustrate how, for this set of events, CME parameters can differ considerably in each catalog. The well-known correlation between CME speed and proton event intensity is shown to be similar for most catalogs, but this is largely because it is determined by a few large ... [READ MORE]
Authors: Ian G. Richardson, Tycho T. von Rosenvinge, Hilary V. Cane
Projects: SoHO-LASCO,STEREO
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Publication Status: Accepted
Last Modified: 2015-05-13 11:34
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Radio Imaging of Shock-accelerated Electrons Associated with an Erupting Plasmoid on 2010 November 3
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Hazel Bain Submitted: 2012-05-03 12:32
We present observations of a metric type II solar radio burst that occurred on the 3rd of November 2010 in association with an erupting plasmoid. The eruption was well observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and the Reuven Ramaty High Energy Solar Spectroscopic Imager, while the burst occurred in the frequency range of the Nan?ay Radioheliograph (NRH). Such events, where the type II emission occurs in the NRH frequency range, allowing us to image the burst, are infrequent. Combining these data sets, we find that the type II is located ahead of the hot (~11 MK) core of the plasmoid, which is surrounded by a well-defined envelope of cool (few MK) plasma. Using two methods, we determine the propagation velocity of the shock: (1) fitting the ... [READ MORE]
Authors: Bain, H. M.; Krucker, S?m; Glesener, L.; Lin, R. P.
Projects: Nan?ay Radioheliograph,RHESSI,SDO-AIA
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Publication Status: Accepted
Last Modified: 2012-05-04 15:01
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Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15
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Laurent Dolla Submitted: 2012-03-28 04:54
We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 15 February
2011, observed simultaneously in several wavebands. We focus on fluctuations on time scale 1?30 s
and find different time lags between different wavebands. During the impulsive phase, the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) channels in the range 25?100 keV lead
all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and
the Extreme Ultra-Violet (EUV) channels of the Euv SpectroPhotometer (ESP) onboard the Solar
Dynamic Observatory (SDO). The Zirconium and Aluminum filter channels of the Large Yield Radiometer
(LYRA) onboard the Project for On-Board Autonomy (PROBA2) satellite and the SXR
channel of ESP follow. The largest ... [READ MORE]
Authors: L. Dolla, C. Marqu?, D. B. Seaton, T. Van Doorsselaere, M. Dominique, D. Berghmans, C. Cabanas, A. De Groof, W. Schmutz, A. Verdini, M. J. West, J. Zender and A. N. Zhukov
Projects: Nobeyama Radioheliograph,PROBA2/LYRA,RHESSI,SDO-AIA,SDO-EVE
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Publication Status: ApJ (published)
Last Modified: 2012-03-28 09:04
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Publication Status: Ap.J. Letters (submitted)
Last Modified: 2003-11-18 14:18
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Publication Status: Accepted by ApJ
Last Modified: 2017-11-17 14:24
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Analysis of a Coronal Mass Ejection and a Co-rotating Interaction Region as they travel from the Sun, passing Venus, Earth, Mars and Saturn
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Ailsa Prise Submitted: 2015-04-21 07:40
During June 2010 a good alignment in the solar system between Venus, STEREO-B, Mars and Saturn provided an excellent opportunity to study the propagation of a Coronal Mass Ejection (CME) and closely occurring Co-rotating Interaction Region (CIR) from the Sun to Saturn. The CME erupted from the Sun at 01:30 UT on 20 June 2010, with v~600 km/s, as observed by STEREO-B, SDO and SOHO/LASCO. It arrived at Venus over 2 days later, some 3.5 days after a CIR is also detected here. The CIR was also observed at STEREO-B and Mars, prior to the arrival of the CME. The CME is not directed Earthward, but the CIR is detected here less than 2 days after its arrival at Mars. Around a month later, a strong compression of the Saturn magnetosphere is observed by Cassini, consistent with the scenario that the ... [READ MORE]
Authors: A. J. Prise, L. K. Harra, S. A. Matthews, C. S. Arridge, N. Achilleos
Projects: ACE,Other,SDO-AIA,SoHO-LASCO,STEREO
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Publication Status: Published
Last Modified: 2015-04-21 10:44
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First Direct Measurements of Transverse Waves in Solar Polar Plumes Using SDO/AIA
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Morton Richard Submitted: 2014-07-08 07:49
There is intense interest in determining the precise contribution of Alfv?nic waves propagating along solar structures to the problems of coronal heating and solar wind acceleration. Since the launch of SDO/AIA, it has been possible to resolve transverse oscillations in off-limb solar polar plumes and recently McIntosh et al. concluded that such waves are energetic enough to play a role in heating the corona and accelerating the fast solar wind. However, this result is based on comparisons to Monte Carlo simulations and confirmation via direct measurements is still outstanding. Thus, this Letter reports on the first direct measurements of transverse wave motions in solar polar plumes. Over a four hour period, we measure the transverse displacements, periods, and velocity amplitudes of 596 ... [READ MORE]
Authors: Thurgood, J. O., Morton, R. J. & McLaughlin, J. A.
Projects: SDO-AIA
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Publication Status: Published in ApJ
Last Modified: 2014-07-08 11:55
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Publication Status: In Print
Last Modified: 2012-10-11 08:03
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Publication Status: Astron. Astrophys., in press
Last Modified: 2010-11-08 07:34
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Publication Status: Published
Last Modified: 2014-01-31 06:38
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Publication Status: Advance in Space Science 39, 1867-1875 (2007), [Proc. COSPAR Meeting 2006, Beijing, China]
Last Modified: 2007-08-02 11:32
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Anisotropic Radio-Wave Scattering and the Interpretation of Solar Radio Emission Observations
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Eduard Kontar Submitted: 2019-09-11 00:02
The observed properties (i.e., source size, source position, time duration, decay time) of solar radio emission produced through plasma processes near the local plasma frequency, and hence the interpretation of solar radio bursts, are strongly influenced by propagation effects in the inhomogeneous turbulent solar corona. In this work, a 3D stochastic description of the propagation process is presented, based on the Fokker-Planck and Langevin equations of radio-wave transport in a medium containing anisotropic electron density fluctuations. Using a numerical treatment based on this model, we investigate the characteristic source sizes and burst decay times for Type III solar radio bursts. Comparison of the simulations with the observations of solar radio bursts shows that predominantly ... [READ MORE]
Authors: Eduard P. Kontar, Xingyao Chen, Nicolina Chrysaphi, Natasha L.S. Jeffrey, A. Gordon Emslie, Vratislav Krupar, Milan Maksimovic, Mykola Gordovskyy, Philippa K. Browning
Projects: ALMA,LOw Frequency ARray (LOFAR),Murchison Widefield Array (MWA),Nan?ay Radioheliograph,Nobeyama Radioheliograph,Owens Valley Solar Array,STEREO,Very Large Array (VLA),Wind
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Publication Status: accepted for publication in The Astrophysical Journal
Last Modified: 2019-09-11 04:19
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Coronal Mass Ejections Associated with Slow Long Duration Flares
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Tomasz Mrozek Submitted: 2013-02-28 02:11
It is well known that there is temporal relationship between coronal mass ejections (CMEs) and associated flares. The duration of the acceleration phase is related to the duration of the rise phase of a flare. We investigate CMEs associated with slow long duration events (LDEs), i.e. flares with the long rising phase. We determined the relationships between flares and CMEs and analyzed the CME kinematics in detail. The parameters of the flares (GOES flux, duration of the rising phase) show strong correlations with the CME parameters (velocity, acceleration during main acceleration phase and duration of the CME acceleration phase). These correlations confirm the strong relation between slow LDEs and CMEs. We also analyzed the relation between the parameters of the CMEs, i.e. a velocity, an ... [READ MORE]
Authors: U. Bak-Steslicka, S. Kolomanski, T. Mrozek
Projects: GOES X-rays ,Other,SoHO-EIT,SoHO-LASCO,Yohkoh-SXT
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Publication Status: Solar Physics, accepted
Last Modified: 2013-02-28 12:33
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Publication Status: Solar Physics, in press
Last Modified: 2015-09-23 13:30
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Publication Status: accepted for publication in Solar Physics
Last Modified: 2012-09-13 10:54
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Publication Status: Published, Solar Physics, 292, 125 (2017), DOI:10.1007/s11207-017-1147-7
Last Modified: 2017-08-29 09:56
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First High-resolution Spectroscopic Observations of an Erupting Prominence Within a Coronal Mass Ejection by the Interface Region Imaging Spectrograph (IRIS)
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Wei Liu Submitted: 2015-02-18 09:56
Spectroscopic observations of prominence eruptions associated with coronal mass ejections (CMEs), although relatively rare, can provide valuable plasma and 3D geometry diagnostics. We report the first observations by the Interface Region Imaging Spectrograph (IRIS) mission of a spectacular fast CME/prominence eruption associated with an equivalent X1.6 flare on 2014 May 9. The maximum plane-of-sky and Doppler velocities of the eruption are 1200 and 460 km/s, respectively. There are two eruption components separated by ~200 km/s in Doppler velocity: a primary, bright component and a secondary, faint component, suggesting a hollow, rather than solid, cone-shaped distribution of material. The eruption involves a left-handed helical structure undergoing counter-clockwise (viewed top-down) ... [READ MORE]
Authors: Wei Liu, Bart De Pontieu, Jean-Claude Vial, Alan M. Title, Mats Carlsson, Han Uitenbroek, Takenori J. Okamoto, Thomas E. Berger, Patrick Antolin
Projects: IRIS,SDO-AIA
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Publication Status: Accepted by ApJ (Feb. 15, 2015), on arxiv since 2015/02/17 - http://arxiv.org/abs/1502.04738
Last Modified: 2015-02-18 13:22
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Quiescent Reconnection Rate Between Emerging Active Regions and Preexisting Field, with Associated Heating: NOAA AR 11112,
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Lucas Tarr Submitted: 2013-12-12 08:47
When magnetic flux emerges from beneath the photosphere it displaces the preexisting field in the corona, and a current sheet generally forms at the boundary between the old and new magnetic domains. Reconnection in the current sheet relaxes this highly stressed configuration to a lower energy state. This scenario is most familiar, and most often studied, in flares, where the flux transfer is rapid. We present here a study of steady, quiescent flux transfer occurring at a rate three orders of magnitude below that in a large flare. In particular we quantify the reconnection rate, and related energy release, occurring as new polarity emerges to form NOAA Active Region 11112 ( extsf{SOL16 October 2010T00:00:00L205C117}) within a region of preexisting flux. A bright, low lying kernel of ... [READ MORE]
Authors: Tarr, L.A., Longcope, D.W., McKenzie, D.E., and Yoshimura, K.
Projects: Hinode/XRT,SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in Solar Physics
Last Modified: 2013-12-12 11:37
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Interaction of Two Filament Channels of Different Chiralities
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Navin Chandra Joshi Submitted: 2016-05-11 03:51
We present observations of interactions between the two filament channels of different chiralities and associated dynamics that occurred during 2014 April 18-20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at the first glance show that the heated plasma is moving from one filament channel to the other. The SDO/AIA 171 A observations and the PFSS magnetic field extrapolation reveal the presence of fan-spine magnetic configuration over the filament channels with a null point located above them. Three different events of filament activations, partial eruptions, and associated filament channel interactions have been observed. The activation initiated in one filament ... [READ MORE]
Authors: Navin Chandra Joshi, Boris Filippov, Brigitte Schmieder, Tetsuya Magara, Young-Jae, Moon, Wahab Uddin
Projects: GONG,SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in ApJ.
Last Modified: 2016-05-11 08:53
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Publication Status: Accepted for publication in ApJ
Last Modified: 2016-03-01 10:07
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A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. II. CMEs, Shock Waves, and Drifting Radio Bursts
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Victor Grechnev Submitted: 2013-08-15 00:32
We continue our study (Grechnev et al. (2013), doi:10.1007/s11207-013-0316-6; Paper I) on the 18 November 2003 geoffective event. To understand possible impact on geospace of coronal transients observed on that day, we investigated their properties from solar near-surface manifestations in extreme ultraviolet, LASCO white-light images, and dynamic radio spectra. We reconcile near-surface activity with the expansion of coronal mass ejections (CMEs) and determine their orientation relative to the earthward direction. The kinematic measurements, dynamic radio spectra, and microwave and X-ray light curves all contribute to the overall picture of the complex event and confirm an additional eruption at 08:07-08:20 UT close to the solar disk center presumed in Paper I. Unusual characteristics of ... [READ MORE]
Authors: V.V. Grechnev, A.M. Uralov, I.M. Chertok, V.A. Slemzin, B.P. Filippov, Ya.I. Egorov, V.G. Fainshtein, A.N. Afanasyev, N.P. Prestage, M. Temmer
Projects: CORONAS-F,GOES X-rays ,Other,RHESSI,SoHO-EIT,SoHO-LASCO,SXI
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Publication Status: Solar Phys., accepted
Last Modified: 2013-08-15 07:53
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Observations of the Thermal and Dynamic Evolution of a Solar Microflare
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Jeffrey Brosius Submitted: 2009-02-24 08:47
We observed a solar microflare over a wide temperature range with three
instruments aboard the SOHO spacecraft (CDS, EIT, & MDI), TRACE (1600
A), GOES, and RHESSI. The microflare's properties and behavior are those
of a miniature flare undergoing gentle chromospheric evaporation, likely driven
by nonthermal electrons. Extreme-ultraviolet spectra were obtained at a rapid
cadence (9.8 s) with CDS in stare mode that included emission lines originating
from the chromosphere (temperature of formation T_m ~ 0.01 MK) and
transition region (TR, ~0.1 MK), to coronal (~1 MK) and flare (T_m ~ 8 MK)
temperatures. Light curves derived from the CDS spectra and TRACE images
(obtained with a variable cadence ~ 34 s) reveal two precursor brightenings
before the microflare. After the ... [READ MORE]
Authors: Brosius, J. W., and Holman, G. D.
Projects: RHESSI,SoHO-EIT,SoHO-MDI,SoHO-CDS,TRACE
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Publication Status: ApJ, 692, 492 (2009 February 10)
Last Modified: 2009-02-25 07:56
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Publication Status: ApJL, subm, 2007-Aug-20
Last Modified: 2007-08-21 08:38
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A Statistical Analysis of the Solar Phenomena Associated with Global EUV Waves
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David Long Submitted: 2017-11-17 08:38
Solar eruptions are the most spectacular events in our solar system and are associated with many different signatures of energy release including solar flares, coronal mass ejections, global waves, radio emission and accelerated particles. Here, we apply the Coronal Pulse Identification and Tracking Algorithm (CorPITA) to the high cadence synoptic data provided by the Solar Dynamic Observatory (SDO) to identify and track global waves observed by SDO. 164 of the 362 solar flare events studied (45%) are found to have associated global waves with no waves found for the remaining 198 (55%). A clear linear relationship was found between the median initial velocity and the acceleration of the waves, with faster waves exhibiting a stronger deceleration (consistent with previous results). No ... [READ MORE]
Authors: David M. Long, Pearse Murphy, Georgina Graham, Eoin P. Carley, David P?rez-Su?rez
Projects: GOES X-rays,SDO-AIA,SoHO-LASCO,Wind
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Publication Status: Accepted for publication in Solar Physics
Last Modified: 2017-11-17 14:24
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The Magnetic Field of Active Region 11158 During the 2011 February 12-17 Flares : Differences between Photospheric Extrapolation and Coronal Forward-Fitting Methods
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Markus J. Aschwanden Submitted: 2014-02-21 09:14
We developed a {sl coronal non-linear force-free field (COR-NLFFF)}
forward-fitting code that fits an approximate {sl non-linear force-free
field (NLFFF)} solution to the observed geometry of automatically traced
coronal loops. In contrast to photospheric NLFFF codes, which calculate
a magnetic field solution from the constraints of the transverse
photospheric field, this new code uses coronal constraints instead, and
this way provides important information on systematic errors of
each magnetic field calculation method, as well as on the non-forcefreeness
in the lower chromosphere. In this study we applied the COR-NLFFF code
to active region NOAA 11158, during the time interval of 2011 Feb 12 to 17,
which includes an X2.2 GOES-class flare plus 35 M and C-class flares.
We ... [READ MORE]
Authors: Aschwanden, M.J., Sun, X.D., and Liu, Y.
Projects: SDO-AIA
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Publication Status: The Astrophysical Journal 785, 34
Last Modified: 2014-03-25 16:21
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Erratum to ?Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23?Paper 1? [J. Atmos. Sol.-Terr. Phys. 70(2?4) (2008) 245?253]
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Nat Gopalswamy Submitted: 2009-07-03 15:08
One of the figures (Fig. 4) in ??Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23 ? Paper 1?? by Gopalswamy et al.(2008, JASTP, Vol.70, Issues 2?4, February 2008, pp. 245?253) is incorrect because of a software error in the routine that was used to make the plot. The source positions of various magnetic cloud (MC) types are therefore not plotted correctly. Fig. 1 replaces Fig.4 in Paper 1 and is now plotted correctly.
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.
Projects: SoHO-EIT,SoHO-LASCO
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Publication Status: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 71, Issue 8-9, p. 1005-1009
Last Modified: 2009-07-04 10:28
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Publication Status: ApJ (in press)
Last Modified: 2017-08-23 12:50
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Publication Status: A&A published
Last Modified: 2010-01-22 06:16
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Publication Status: Published-2005
Last Modified: 2005-12-29 05:46
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Publication Status: Accepted by ApJ
Last Modified: 2016-05-10 13:48
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Publication Status: Published: Living Rev. Solar Phys., 9 (2012) 6
Last Modified: 2012-12-01 23:52
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APPEARANCES AND STATISTICS OF CORONAL CAVITIES DURING THE ASCENDING PHASE OF SOLAR CYCLE 24
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Nishu Karna Submitted: 2015-09-14 11:09
We present a survey of 429 coronal prominence cavities found between 2010 May and 2015 February using the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly limb synoptic maps. We examined correlations between each cavity's height, width, and length. Our findings showed that around 38% of the cavities were prolate, 27% oblate, and 35% circular in shape. The lengths of the cavities ranged from 0.06 to 2.9 ${R}_{\odot }$. When a cavity is longer than 1.5 ${R}_{\odot }$, it has a narrower height range (0.1?0.3 ${R}_{\odot }$), whereas when the cavity was shorter than 1.5 ${R}_{\odot }$, it had a wider height range (0.07?0.5 ${R}_{\odot }$). We find that the overall three-dimensional topology of the long, stable cavities can be characterized as a long tube with an elliptical cross ... [READ MORE]
Authors: N. Karna, W. D. Pesnell, and J. Zhang
Projects: SDO-AIA,SDO-HMI
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Publication Status: Published (Sep 8, 2015)
Last Modified: 2015-09-14 16:09
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The large longitudinal spread of solar energetic particles during the January 17, 2010 solar event
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Nina Dresing Submitted: 2012-06-08 02:03
We investigate multi-spacecraft observations of the January 17, 2010 solar energetic particle event. Energetic electrons and protons have been observed over a remarkable large longitudinal range at the two STEREO spacecraft and SOHO suggesting a longitudinal spread of nearly 360 degrees at 1,AU. The flaring active region, which was on the backside of the Sun as seen from Earth, was separated by more than 100 degrees in longitude from the magnetic footpoints of each of the three spacecraft. The event is characterized by strongly delayed energetic particle onsets with respect to the flare and only small or no anisotropies in the intensity measurements at all three locations. The presence of a coronal shock is evidenced by the observation of a type II radio burst from the Earth and ... [READ MORE]
Authors: N. Dresing, R.Gomez-Herrero, A. Klassen, B. Heber, Y. Kartavykh, W. Dr?ge
Projects: ACE,GONG,SoHO-EIT,STEREO
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Publication Status: accepted
Last Modified: 2012-06-28 03:59
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Properties of slow magnetoacoustic oscillations of solar coronal loops by multi-instrumental observations
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Valery Nakariakov Submitted: 2019-03-05 08:52
Rapidly decaying oscillations of the thermal emission detected in the decay phase of solar and stellar flares are usually interpreted as standing or sloshing (reflecting) slow magnetoacoustic oscillations. We determine the scalings of the oscillation periods, damping times and amplitudes with the temperature, considering both standing and sloshing oscillations detected with different instruments. In addition, the time evolution of different spatial harmonics of a sloshing oscillation is considered. Parameters of slow oscillations observed in the EUV, X-ray, and microwave bands, and published in the literature, are used. The damping time of slow oscillations is found to scale almost linearly with the oscillation period, as the period to $0.87\pm 0.1$, giving the average Q-factor determined ... [READ MORE]
Authors: Nakariakov, V. M., Kosak, M. K., Kolotkov, D. Y., Anfinogentov, S. A., Kumar, P., Moon, Y.-J.
Projects: SDO-AIA
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Publication Status: ApJL, accepted
Last Modified: 2019-03-05 12:47
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Automated Solar Feature Detection for Space Weather Applications
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David Perez-Suarez Submitted: 2011-10-05 20:15
The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometres per hour in a matter of minutes, making their automated detection and characterisation challenging. Additionally, there are numerous faint solar features, such as coronal holes and coronal dimmings, which are important for space weather monitoring and forecasting, but their low intensity and sometimes transient nature makes them problematic to detect using traditional image processing techniques. These difficulties are compounded by advances in ground- and space- based instrumentation, which have increased the volume of data that solar physicists are ... [READ MORE]
Authors: David Perez-Suarez, Paul A. Higgins, D. Shaun Bloomfield, R.T. James McAteer, Larisza D. Krista, Jason P. Byrne, Peter. T. Gallagher
Projects: SDO-AIA
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Publication Status: Book chapter in -Applied Signal and Image Processing: Multidisciplinary Advancements- (ed. Rami Qahwaji, Roger Green and Evor L. Hines) pp. 207-225
Last Modified: 2011-10-05 20:15
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Coronal Loop Scaling Laws for Various Forms of Parallel Heat Conduction
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Eduard Kontar Submitted: 2019-07-30 08:55
The solar atmosphere is dominated by loops of magnetic fluxes that connect the multi-million degree corona to the much cooler chromosphere. The temperature and density structure of quasi-static loops are determined by the continuous flow of energy from the hot corona to the lower solar atmosphere. Loop scaling laws provide relationships between global properties of the loop (such as the peak temperature, pressure, and length); they follow from the physical variable dependencies of various terms in the energy equation, and, hence, the form of the loop scaling law provides insight into the key physics that control the loop structure. Traditionally, scaling laws have been derived under the assumption of collision-dominated thermal conduction. Here, we examine the impact of different regimes ... [READ MORE]
Authors: Stephen J. Bradshaw, A. Gordon Emslie, N. H. Bian, and Eduard P. Kontar
Projects: Fermi/GBM,GOES X-rays,RHESSI,SDO-AIA,TRACE
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Publication Status: ApJ in press
Last Modified: 2019-07-31 12:12
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Publication Status: The manuscript has been accepted for publication in the Journal of Space Weather and Space Climate (SWSC)
Last Modified: 2018-02-05 22:08
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Publication Status: Accepted to Solar Physics (Topical Issue, "Exploring the Network of SDO Science")
Last Modified: 2014-04-02 12:11
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Simultaneous observation of a flux rope eruption and magnetic reconnection during an X-class solar flare
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Xiaoli Yan Submitted: 2018-01-10 18:06
In this letter, we present a spectacular eruptive flare (X8.2) associated with a coronal mass ejection (CME) on 2017 September 10 at the west limb of the Sun. A flux rope eruption is followed by the inflow, the formation of a current sheet and a cusp structure, which were simultaneously observed during the occurrence of this flare. The hierarchical layers of the cusp-shaped structure are well observed in 131 \AA\ observation. The scenario that can be created from these observations is very consistent with the predictions of some eruptive models. Except for the characteristics mentioned above in the process of the flare predicted by classical eruption models, the current sheet separating into several small current sheets is also observed at the final stage of the flux rope eruption. The ... [READ MORE]
Authors: X. L. Yan, L. H. Yang, Z. K. Xue, Z. X. Mei, D. F. Kong, J. C. Wang, Q. L. Li
Projects: SDO-AIA
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Publication Status: Accepted for publication in ApJL
Last Modified: 2018-01-14 00:01
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Publication Status: Solar Physics, 2006, Vol 236, 325-349
Last Modified: 2007-01-11 11:56
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Rapid Fluctuations in the Lower Solar Atmosphere
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John K Lawrence Submitted: 2011-11-23 16:01
The Rapid Oscillations in the Solar Atmosphere (ROSA) instrument reveals
solar atmospheric fluctuations at high frequencies. Spectra of variations of
the G-band intensity (IG) and CaII K-line intensity (IK) show correlated
fluctuations above white noise to frequencies beyond 300 mHz and 50 mHz,
respectively. The noise-corrected G-band spectrum for f = 28 - 326 mHz shows a
power law with exponent -1.21 pm, 0.02, consistent with the presence of
turbulent motions. G-band spectral power in the 25 - 100 mHz ('UHF') range is
concentrated at the locations of magnetic bright points in the intergranular
lanes and is highly intermittent in time. The intermittence of the UHF G-band
fluctuations, shown by a positive kurtosis {kappa}, also suggests turbulence.
Combining values of IG, IK, UHF power, ... [READ MORE]
Authors: J.K. Lawrence, A.C. Cadavid, D.J. Christian, D.B. Jess and M. Mathioudakis
Projects: National Solar Observatory (Sac Peak)
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Publication Status: 2011 ApJ, 743, L24
Last Modified: 2011-11-24 02:52
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Quasi-periodic fast propagating magnetoacoustic waves during the magnetic reconnection between solar coronal loops
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Leping Li Submitted: 2018-11-21 18:38
Employing Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) multi-wavelength im- ages, we have presented coronal condensations caused by magnetic reconnection between a system of open and closed solar coronal loops. In this Letter, we report the quasi-periodic fast magnetoacoustic waves propagating away from the reconnection region upward across the higher-lying open loops dur- ing the reconnection process. On 2012 January 19, reconnection between the higher-lying open loops and lower-lying closed loops took place, and two sets of newly reconnected loops formed. Thereafter, cooling and condensations of coronal plasma occurred in the magnetic dip region of higher-lying open loops. During the reconnection process, disturbances originating from the reconnection region prop- agate ... [READ MORE]
Authors: Li, L. P., Zhang, J., Peter, H., Chitta, L. P., Su, J. T., Song, H. Q., Xia, C., Hou, Y. J.
Projects: SDO-AIA
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Publication Status: accepted for publication in ApJL
Last Modified: 2018-11-22 20:10
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Solar Coronal Jets: Observations, Theory, and Modeling
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Nour E. Raouafi Submitted: 2016-07-06 15:34
Coronal jets represent important manifestations of ubiquitous solar transients, which may be the source of significant mass and energy input to the upper solar atmosphere and the solar wind. While the energy involved in a jet-like event is smaller than that of ?nominal? solar flares and coronal mass ejections (CMEs), jets share many common properties with these phenomena, in particular, the explosive magnetically driven dynamics. Studies of jets could, therefore, provide critical insight for understanding the larger, more complex drivers of the solar activity. On the other side of the size-spectrum, the study of jets could also supply important clues on the physics of transients close or at the limit of the current spatial resolution such as spicules. Furthermore, jet phenomena may hint ... [READ MORE]
Authors: N.E. Raouafi, S. Patsourakos, E. Pariat, P.R. Young, A.C. Sterling, A. Savcheva, M. Shimojo, F. Moreno-Insertis, C.R. DeVore, V. Archontis, T. T?r?k, H. Mason, W. Curdt, K. Meyer, K. Dalmasse, Y. Matsui
Projects: GOES X-rays ,Hinode/EIS,Hinode/SOT,Hinode/XRT,IRIS,Nobeyama Radioheliograph,RHESSI,SDO-AIA,SDO-HMI,SoHO-EIT,SoHO-MDI,SoHO-CDS,SoHO-LASCO,SoHO-SUMER,STEREO,TRACE,Yohkoh-HXT,Yohkoh-SXT
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Publication Status: Published in Space Science Reviews. doi: 10.1007/s11214-016-0260-5
Last Modified: 2016-07-07 09:18
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Bridging the Gap: Capturing the Lyα Counterpart of a Type-II Spicule and its Heating Evolution with VAULT2.0 and IRIS Observations
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Georgios Chintzoglou Submitted: 2018-03-11 23:32
We present results from an observing campaign in support of the VAULT2.0 sounding rocket launch on September 30, 2014. VAULT2.0 is a Lyα (1216 ?) spectroheliograph capable of providing spectroheliograms at high cadence. Lyα observations are highly complementary to the IRIS observations of the upper chromosphere and the low transition region (TR) but have previously been unavailable. The VAULT2.0 data provide new constraints on upper-chromospheric conditions for numerical models. The observing campaign was closely coordinated with the IRIS mission. Taking advantage of this simultaneous multi-wavelength coverage of target AR 12172 and by using state-of-the-art radiative-MHD simulations of spicules, we investigate in detail a type-II spicule associated with a fast (300 km ... [READ MORE]
Authors: Georgios Chintzoglou, Bart De Pontieu, Juan Mart?nez-Sykora, Tiago M.D. Pereira, Angelos Vourlidas, Samuel Tun Beltran
Projects: IRIS,SDO-AIA,SDO-HMI,Very high-Angular resolution Ultraviolet Telescope 2.0 (VAULT2)
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Publication Status: Accepted for publication to the Astrophysical Journal
Last Modified: 2018-03-12 09:45
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Publication Status: Proceedings of 'SOHO 13 - Waves, Oscillations and Small-Scale Transient Events in the Solar Atmosphere: A Joint View from SOHO and TRACE'. 29 September - 3 October 2003, Palma de Mallorca, Balearic Islands, Spain (ESA SP-547, January 2004). Compiled by: H
Last Modified: 2005-11-21 08:54
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A Tiny Eruptive Filament as a Flux-Rope Progenitor and Driver of a Large-Scale CME and Wave
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Victor Grechnev Submitted: 2016-04-04 21:36
A solar eruptive event SOL2010-06-13 observed with the \textit{Atmospheric Imaging Assembly} (AIA) of the \textit{Solar Dynamics Observatory} (SDO) has been extensively discussed in the contexts of the CME development and an associated extreme-ultraviolet (EUV) wave-like transient in terms of a shock driven by the apparent CME rim. Continuing the analysis of this event, we have revealed an erupting flux rope, studied its properties, and detected wave signatures inside the developing CME. These findings have allowed us to establish new features in the genesis of the CME and associated EUV wave and to reconcile all of the episodes into a single causally-related sequence. (1) A hot 11 MK flux rope developed from the structures initially associated with a compact filament system. The flux ... [READ MORE]
Authors: V.V. Grechnev, A.M. Uralov, A.A. Kochanov, I.V. Kuzmenko, D.V. Prosovetsky, Ya.I. Egorov, V.G. Fainshtein, L.K. Kashapova
Projects: None,GOES X-rays ,SDO-AIA,SDO-HMI,SoHO-LASCO,STEREO
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Publication Status: Accepted for publication in Solar Physics. DOI: 10.1007/s11207-016-0888-z
Last Modified: 2016-04-06 08:20
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The Role of Erupting Sigmoid in Triggering a Flare with Parallel and Large-Scale Quasi-Circular Ribbons
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Navin Chandra Joshi Submitted: 2015-09-07 21:28
In this paper, we present observations and analysis of an interesting sigmoid formation, eruption and the associated flare that occurred on 2014 April 18 using multi-wavelength data sets. We discuss the possible role of the sigmoid eruption in triggering the flare, which consists of two different set of ribbons: parallel ribbons as well as a large-scale quasi-circular ribbon. Several observational evidence and nonlinear force-free field extrapolation results show the existence of a large-scale fan-spine type magnetic configuration with a sigmoid lying under a section of the fan dome. The event can be explained with the following two phases. During the pre-flare phase, we observed the formation and appearance of sigmoid via tether-cutting reconnection between the two sets of sheared fields ... [READ MORE]
Authors: Navin Chandra Joshi, Chang Liu, Xudong Sun, Haimin Wang, Tetsuya Magara, Y.-J. Moon
Projects: RHESSI,SDO-AIA,SDO-HMI
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Publication Status: Accepted for Publication in ApJ
Last Modified: 2015-09-08 05:18
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Publication Status: A&A, accepted
Last Modified: 2008-10-01 09:47
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Publication Status: Climate andWeather of the Sun-EarthSystem(CAWSES):SelectedPapers from the2007KyotoSymposium, Edited by T. Tsuda, R. Fujii, K. Shibata, and M. A. Geller, pp. 77?120. TERRAPUB, Tokyo, 2009.
Last Modified: 2009-07-04 10:27
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Coronal magnetic reconnection driven by CME expansion - The 2011 June 7 event
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Lidia van Driel-Gesztelyi Submitted: 2014-06-12 03:28
Coronal mass ejections (CMEs) erupt and expand in a magnetically structured solar corona. Various indirect observational pieces of evidence have shown that the magnetic field of CMEs reconnects with surrounding magnetic fields, forming, e.g., dimming regions distant from the CME source regions. Analyzing Solar Dynamics Observatory (SDO) observations of the eruption from AR 11226 on 2011 June 7, we present the first direct evidence of coronal magnetic reconnection between the fields of two adjacent ARs during a CME. The observations are presented jointly with a data-constrained numerical simulation, demonstrating the formation/intensification of current sheets along a hyperbolic flux tube (HFT) at the interface between the CME and
the neighbouring AR 11227. Reconnection resulted in the ... [READ MORE]
Authors: L. van Driel-Gesztelyi, D. Baker, T. T?r?k, E. Pariat, L.M. Green, D.R. Williams, J. Carlyle, G. Valori, P. D?moulin, B. Kliem, D. Long, S.A. Matthews, J.-M. Malherbe
Projects: SDO-AIA
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Publication Status: Published in ApJ 788, 85 (2014)
Last Modified: 2014-06-12 14:54
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Publication Status: AGU Monograph of AGU Chapman Conference ``Solar Energetic Plasmas and Particles'', Turku, Finland, 2-6 August 2004, (eds. Nat Go
Last Modified: 2005-03-01 09:40
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CME-driven shock and Type II solar radio burst band-splitting
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Nicolina Chrysaphi Submitted: 2018-11-13 05:13
Coronal Mass Ejections (CMEs) are believed to be effective in producing shocks in the solar corona and the interplanetary space. One of the important signatures of shocks and shock acceleration are Type II solar radio bursts that drift with the shock speed and produce bands of plasma fundamental and higher harmonic radio emission. An intriguing aspect of Type II radio bursts is the occasional split of a harmonic band into thinner lanes, known as band-splitting. Here, we report a detailed imaging and spectroscopic observation of a CME-driven shock producing band-splitting in a Type II burst. Using the Low Frequency Array (LOFAR), we examine the spatial and temporal relation of the Type II burst to the associated CME event, use source imaging to calculate the apparent coronal density, and ... [READ MORE]
Authors: Chrysaphi, N., Kontar E. P., Holman, G. D., and Temmer, M.
Projects: LOw Frequency ARray (LOFAR),SDO-AIA,SoHO-LASCO
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Publication Status: ApJ (in press)
Last Modified: 2018-11-14 12:12
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Flare differentially rotates sunspot on Sun's surface
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Chang Liu Submitted: 2016-10-10 08:28
Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ~50° h^{-1}) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change ... [READ MORE]
Authors: Chang Liu, Yan Xu, Wenda Cao, Na Deng, Jeongwoo Lee, Hugh S. Hudson, Dale E. Gary, Jiasheng Wang, Ju Jing & Haimin Wang
Projects: BBSO/NST,Fermi/GBM,GOES X-rays,SDO-HMI
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Publication Status: Published in Nature Communications
Last Modified: 2016-10-12 15:08
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Publication Status: A&A, 2009, vol. 508, pp. 1485
Last Modified: 2010-06-28 09:15
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Publication Status: Accepted for publication in Solar Physics
Last Modified: 2017-08-07 12:04
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Publication Status: accepted for publication in ApJ
Last Modified: 2016-07-20 12:23
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Slipping magnetic reconnection during an X-class solar flare observed by SDO/AIA
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Jaroslav Dudik Submitted: 2014-01-30 03:22
We present SDO/AIA observations of an eruptive X-class flare of July 12, 2012, and compare its evolution with the predictions of a 3D numerical simulation. We focus on the dynamics of flare loops that are seen to undergo slipping reconnection during the flare. In the AIA 131A observations, lower parts of 10 MK flare loops exhibit an apparent motion with velocities of several tens of km/s along the developing flare ribbons. In the early stages of the flare, flare ribbons consist of compact, localized bright transition-region emission from the footpoints of the flare loops. A DEM analysis shows that the flare loops have temperatures up to the formation of Fe XXIV. A series of very long, S-shaped loops erupt, leading to a CME observed by STEREO. The observed dynamics are compared with the ... [READ MORE]
Authors: J. Dudik, M. Janvier, G. Aulanier, G. Del Zanna, M. Karlicky, H. Mason, B. Schmieder
Projects: SDO-AIA
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Publication Status: The Astrophysical Journal, accepted
Last Modified: 2014-01-30 10:51
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Publication Status: Solar Physics; under revision
Last Modified: 2017-03-14 11:47
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Relationship between EUV microflares and small-scale magnetic fields in the quiet Sun
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Fayu Jiang Submitted: 2015-02-12 18:59
Microflares are small dynamic signatures observed in X-ray and extreme-ultraviolet channels. Because of their impulsive emission enhancements and wide distribution, they are thought to be closely related to coronal heating. By using the high resolution 171 {\AA} images from the Atmospheric Imaging Assembly and the lines-of-sight magnetograms obtained by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, we trace 10794 microflares in a quiet region near the disk center with a field of view of 960 arcsec \times 1068 arcsec during 24 hr. The microflares have an occurrence rate of 4.4 \times 10^3 hr^−1 extrapolated over the whole Sun. Their average brightness, size, and lifetime are 1.7 I_0(of the quiet Sun), 9.6 Mm^2, and 3.6 min, respectively. There exists ... [READ MORE]
Authors: Fayu Jiang, Jun Zhang, Shuhong Yang
Projects: SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in Publications of the Astronomical Society of Japan
Last Modified: 2015-02-14 22:11
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The 26 December 2001 Solar Eruptive Event Responsible for GLE63. III. CME, Shock Waves, and Energetic Particles
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Valentin Kiselev Submitted: 2016-12-13 22:32
The 26 December 2001 moderate solar eruptive event (GOES importance M7.1, microwaves up to 4000 sfu at 9.4 GHz, CME speed 1446 km/s) produced strong fluxes of solar energetic particles (SEPs) and ground-level enhancement of cosmic-ray intensity (GLE63). To find a possible reason for the atypically high proton outcome of this event, we study its multi-wavelength images and dynamic radio spectra, and quantitatively reconcile the findings with each other. An additional eruption probably occurred in the same active region about half an hour before the main eruption, which produced two blast-wave-like shocks during the impulsive phase. Later on, the two shock waves merged around the frontal direction into a single shock, which is traced up to 25 solar radii as a halo ahead of the expanding CME ... [READ MORE]
Authors: Grechnev, V. V., Kiselev, V. I., Uralov, A. M., Klein, K.-L., Kochanov, A.A.
Projects: GOES Particles,GOES X-rays,Nobeyama Radioheliograph,SoHO-EIT,SoHO-LASCO,TRACE,Wind
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Publication Status: Solar Physics, submitted
Last Modified: 2016-12-14 13:56
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High-Energy Aspects of Solar Flares: Overview of the Volume
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Amir Caspi Submitted: 2011-10-28 12:13
In this introductory chapter, we provide a brief summary of the successes and
remaining challenges in understanding the solar flare phenomenon and its
attendant implications for particle acceleration mechanisms in astrophysical
plasmas. We also provide a brief overview of the contents of the other chapters
in this volume, with particular reference to the well-observed flare of 2002
July 23
Authors: Brian R. Dennis, A. Gordon Emslie, Hugh S. Hudson
Projects: GONG,Hinode/EIS,Hinode/SOT,Hinode/XRT,Nobeyama Radioheliograph,Owens Valley Solar Array,RHESSI,SDO-AIA,SDO-HMI,SDO-EVE,SoHO-EIT,SoHO-MDI,SoHO-CDS,SoHO-LASCO,SoHO-SUMER,STEREO,TRACE
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Publication Status: Published -- Dennis, B. R., et al. 2011, Space Sci. Rev., 159, 3; DOI 10.1007/s11214-011-9802-z
Last Modified: 2011-11-17 14:17
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On a Coronal Blowout Jet: The First Observation of a Simultaneously Produced Bubble-like CME and a Jet-like CME in a Solar Event
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Yuandeng Shen Submitted: 2012-05-01 20:06
The coronal blowout jet is a peculiar category among various jet phenomena, in which the sheared base arch, often carrying a small filament, experiences a miniature version of blowout eruption that produces large-scale coronal mass ejection (CME). In this paper, we report such a coronal blowout jet with high-resolution multi-wavelength and multi-angle observations taken from Solar Dynamics Observatory, Solar Terrestrial Relations Observatory, and Big Bear Solar Observatory. For the first time, we find that simultaneous bubble-like and jet-like CMEs were dynamically related to the blowout jet that showed cool and hot components next to each other. Our observational results indicate that (1) the cool component resulted from the eruption of the filament contained within the jet's base arch, ... [READ MORE]
Authors: Yuandeng Shen, Yu Liu, Jiangtao Su, and Yuanyong Deng
Projects: SDO-AIA
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Publication Status: It has been published by ApJ (2012, ApJ, 745, 164).
Last Modified: 2012-05-02 11:15
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Quasi-periodic Pulsations in a Solar Microflare
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Valery Nakariakov Submitted: 2018-06-07 11:07
Irregular time evolution of the radio emission generated in a B2-class microflare (SOL2017-01-25T10:15), occurring on 2017 January 25 in active region 12,628, is studied. The microflare was apparently initiated by an appearance of an s-shaped loop, observed in the EUV band. The radio emission is associated with the nonthermal electrons detected with Ramaty High Energy Solar Spectroscopic Imager, and originates simultaneously from two opposite footpoints of a magnetic fan structure beginning at a sunspot. According to the active region geometry, the footpoints are situated in the meridional direction, and hence are observed by RATAN-600 simultaneously. The radio emission intensity signal, as well as the left-hand and right-hand circular polarization signals in the low-frequency band (3-4 ... [READ MORE]
Authors: Nakariakov, V. M., Anfinogentov, S., Storozhenko, A. A., Kurochkin, E. A., Bogod, V. M., Sharykin, I. N., Kaltman, T. I.
Projects: RATAN-600
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Publication Status: ApJ 859:154, 2018
Last Modified: 2018-06-07 12:36
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Publication Status: ApJ (accepted)
Last Modified: 2013-12-19 07:43
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Publication Status: A&A Letter, in press
Last Modified: 2019-03-19 10:44
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Observing the Sun with Atacama Large Millimeter/submillimeter Array (ALMA): High Resolution Interferometric Imaging
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Masumi Shimojo Submitted: 2017-05-22 02:18
Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submillimeter wavelengths are challenging due to the intense, extended, low- contrast, and dynamic nature of emission from the quiet Sun, and the extremely intense and variable nature of emissions associated with energetic phenomena. The Atacama Large Millimeter/submillimeter Array (ALMA) was designed with solar observations in mind. The requirements for solar observations are significantly different from observations of sidereal sources and special ... [READ MORE]
Authors: M. Shimojo, T.S. Bastian, A.S. Hales, S.M. White, K. Iwai, R.E. Hills, A. Hirota, N.M. Phillips, T. Sawada, P. Yagoubov, G. Siringo, S. Asayama, M. Sugimoto, R. Brajsa, I. Skokic, M. Barta, S. Kim, I. de Gregorio, S.A. Corder, H.S. Hudson, S. Wedemeyer, D.E. Gary, B. De Pontieu, M. Loukitcheva, G.D. Fleishman, B. Chen, A. Kobelski, Y. Yan
Projects: ALMA
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Publication Status: Accepted for publication in Solar Physics
Last Modified: 2017-05-24 14:23
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Publication Status: Accepted for publication in Solar Physics
Last Modified: 2011-11-30 08:16
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Publication Status: ApJ (subm) - Dec 2006
Last Modified: 2006-12-20 11:35
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Publication Status: Astrophysical Journal, in press
Last Modified: 2018-02-28 13:59
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Publication Status: submitted to Solar Physics
Last Modified: 2012-09-13 10:14
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A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. IV. Unusual Magnetic Cloud and Overall Scenario
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Victor Grechnev Submitted: 2014-09-02 00:06
The geomagnetic superstorm of 20 November 2003 with Dst = -422 nT, one of the most intense in history, is not well understood. The superstorm was caused by a moderate solar eruptive event on 18 November, comprehensively studied in our preceding Papers I-III. The analysis has shown a number of unusual and extremely complex features, which presumably led to the formation of an isolated right-handed magnetic-field configuration. Here we analyze the interplanetary disturbance responsible for the 20 November superstorm, compare some of its properties with the extreme 28-29 October event, and reveal a compact size of the magnetic cloud (MC) and its disconnection from the Sun. Most likely, the MC had a spheromak configuration and expanded in a narrow angle of < 14 degree. A very strong magnetic ... [READ MORE]
Authors: V. V. Grechnev, A. M. Uralov, I. M. Chertok, A. V. Belov, B. P. Filippov, V. A. Slemzin, B. V. Jackson
Projects: ACE,Neutron Monitors,Other
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Publication Status: Solar Phys., accepted
Last Modified: 2014-09-03 13:11
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Publication Status: ApJ 686, L127-L130
Last Modified: 2008-12-02 09:30
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Publication Status: ApJ, in press
Last Modified: 2018-05-02 12:06
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Publication Status: to be accepted for publication by A&A
Last Modified: 2016-11-30 12:19
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Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era
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Nat Gopalswamy Submitted: 2008-02-08 15:32
Using the extensive and uniform data on coronal mass ejections (CMEs), solar energetic particle (SEP) events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfv?n speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and ... [READ MORE]
Authors: N. Gopalswamy, S. Yashiro, S. Akiyama, P. Makela, H. Xie, M. Kaiser, R. Howard, and J.-L. Bougeret
Projects: SoHO-EIT,SoHO-LASCO
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Publication Status: Annales Geophysicae, Accepted for Publication, February 7, 2008
Last Modified: 2008-02-09 21:49
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Chain Reconnections observed in Sympathetic Eruptions
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Navin Chandra Joshi Submitted: 2016-02-25 21:22
The nature of various plausible causal links between sympathetic events is still a controversial issue. In this work, we present multi-wavelength observations of sympathetic eruptions, associated flares and coronal mass
ejections (CMEs) occurring on 2013 November 17 in two close-by active regions. Two filaments i.e., F1 and F2 are observed in between the active regions. Successive magnetic reconnections, caused by different reasons (flux
cancellation, shear and expansion) have been identified during the whole event. The first reconnection occurred during the first eruption via flux cancellation between the sheared arcades overlying filament F2, creating a flux rope and leading to the first double ribbon solar flare. During this phase we observed the eruption of overlaying arcades and ... [READ MORE]
Authors: Navin Chandra Joshi, Brigitte Schmieder, Tetsuya Magara, Yang Guo, Guillaume Aulanier
Projects: GOES Particles,GONG,RHESSI,SDO-AIA,SDO-HMI,SoHO-LASCO,STEREO
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Publication Status: Accepted for publication in ApJ
Last Modified: 2016-02-29 10:55
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Title: Monte Carlo Markov Chain DEM reconstruction of isothermal plasmas
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Fabio Reale Submitted: 2011-12-14 03:36
In this paper, we carry out tests on the Monte Carlo Markov Chain (MCMC)
technique with the aim of determining: 1) its ability to retrieve isothermal
plasmas from a set of spectral line intensities, with and without random noise;
2) to what extent can it discriminate between an isothermal solution and a
narrow multithermal distribution; and 3) how well it can detect multiple
isothermal components along the line of sight. We also test the effects of 4)
atomic data uncertainties on the results, and 5) the number of ions whose lines
are available for the DEM reconstruction. We find that the MCMC technique is
unable to retrieve isothermal plasmas to better than Delta log T = 0.05. Also,
the DEM curves obtained using lines calculated with an isothermal plasma and
with a Gaussian distribution ... [READ MORE]
Authors: E. Landi, F. Reale, P. Testa
Projects: Hinode/EIS,Hinode/XRT,SDO-AIA,SDO-EVE,SoHO-CDS,SoHO-SUMER
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Publication Status: accepted for publication in A&A
Last Modified: 2011-12-14 08:53
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Publication Status: Published, The Astrophysical Journal, 855:109 (10pp), 2018
Last Modified: 2018-03-16 13:38
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Publication Status: Solar Physics (to be published)
Last Modified: 2012-12-14 16:10
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Investigating the Dynamics and Density Evolution of Returning Plasma Blobs from the 2011 June 7 Eruption
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Jack Carlyle Submitted: 2014-01-22 23:53
This work examines infalling matter following an enormous Coronal Mass Ejection (CME) on 2011 June 7. The material formed discrete concentrations, or blobs, in the corona and fell back to the surface, appearing as dark clouds against the bright corona. In this work we examined the density and dynamic evolution of these blobs in order to formally assess the intriguing morphology displayed throughout their descent. The blobs were studied in five wavelengths (94, 131, 171, 193 and 211 Angstrom) using the Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO/AIA), comparing background emission to attenuated emission as a function of wavelength to calculate column densities across the descent of four separate blobs. We found the material to have a column density of hydrogen of ... [READ MORE]
Authors: Jack Carlyle, David R. Williams, Lidia van Driel-Gesztelyi, Davina Innes, Andrew Hillier, Sarah Matthews
Projects: SDO-AIA
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Publication Status: In press, ApJ
Last Modified: 2014-01-23 10:23
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Large-scale Coronal Propagating Fronts in Solar Eruptions as Observed by the Atmospheric Imaging Assembly on Board the Solar Dynamics Observatory - An Ensemble Study
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Nariaki Nitta Submitted: 2013-08-18 21:49
This paper presents a study of a large sample of global disturbances in the solar corona with characteristic propagating fronts as intensity enhancement, similar to the phenomena that have often been referred to as EIT waves or EUV waves. Now Extreme Ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) provide a significantly improved view of these large-scale coronal propagating fronts (LCPFs). Between April 2010 and January 2013, a total of 171 LCPFs have been identified through visual inspection of AIA images in the 193 A channel. Here we focus on the 138 LCPFs that are seen to propagate across the solar disk, first studying how they are associated with flares, coronal mass ejections (CMEs) and type II radio bursts. ... [READ MORE]
Authors: Nitta, N. V., Schrijver, C. J., Title, A. M., Liu, W.
Projects: SDO-AIA
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Publication Status: Published, 2013, ApJ, 776, 58
Last Modified: 2014-09-22 21:07
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Witnessing a Large-scale Slipping Magnetic Reconnection along a Dimming Channel during a Solar Flare
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Ju Jing Submitted: 2017-06-12 15:24
We report the intriguing large-scale dynamic phenomena associated with the M6.5 flare (SOL2015-06-22T18:23) in NOAA active region 12371, observed by RHESSI, Fermi, and the Atmospheric Image Assembly (AIA) and Magnetic Imager (HMI) on the Solar Dynamic Observatory (SDO). The most interesting feature of this event is a third ribbon (R3) arising in the decay phase, propagating along a dimming channel (seen in EUV passbands) towards a neighboring sunspot. The propagation of R3 occurs in the presence of hard X-ray footpoint emission, and is broadly visible at temperatures from 0.6 MK to over 10 MK through the Differential Emission Measure (DEM) analysis. The coronal loops then undergo an apparent slipping motion following the same path of R3, after a ~80 min delay. To understand the underlying ... [READ MORE]
Authors: Ju Jing, Rui Liu, Mark C. M. Cheung, Jeongwoo Lee, Yan Xu, Chang Liu, Chunming Zhu, and Haimin Wang
Projects: Fermi/GBM,RHESSI,SDO-AIA,SDO-HMI
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Publication Status: accepted for publication in ApJL
Last Modified: 2017-06-14 10:02
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How did a Major Confined Flare Occur in Super Solar Active Region 12192?
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Chaowei Jiang Submitted: 2016-06-30 21:31
We study the physical mechanism of a major X-class solar flare that occurred in the super NOAA active region (AR) 12192 using a data-driven numerical magnetohydrodynamic (MHD) modeling complemented with observations. With the evolving magnetic fields observed at the solar surface as bottom boundary input, we drive an MHD system to evolve self-consistently in correspondence with the realistic coronal evolution. During a two-day time interval, the modeled coronal field has been slowly stressed by the photospheric field evolution,which gradually created a large-scale coronal current sheet, i.e., a narrow layer with intense current, in the core of the AR. The current layer was successively enhanced until it became so thin that a tether-cutting reconnection between the sheared magnetic arcades ... [READ MORE]
Authors: Chaowei Jiang, Shi Tsan Wu, Vasyl B Yurchyshyn, Haimin Wang, Xueshang Feng, Qiang Hu
Projects: SDO-AIA,SDO-HMI
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Publication Status: accept by ApJ
Last Modified: 2016-07-06 10:36
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Twisting solar coronal jet launched at the boundary of an active region
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Guillaume Aulanier Submitted: 2013-09-20 02:41
A broad jet was observed in a weak magnetic field area at the edge of active region NOAA
11106 that also produced other nearby recurring and narrow jets. The peculiar shape and magnetic
environment of the broad jet raised the question of whether it was created by the same
physical processes of previously studied jets with reconnection occurring high in the corona.
We carried out a multi-wavelength analysis using the EUV images from the
Atmospheric Imaging Assembly (AIA) and magnetic fields from the Helioseismic and Magnetic
Imager (HMI) both on-board the SDO satellite, which we coupled to a high-resolution, nonlinear
force-free field extrapolation. Local correlation tracking was used to identify the photospheric
motions that triggered the jet, and time-slices were extracted along ... [READ MORE]
Authors: Schmieder B., Guo Y., Moreno-Insertis F., Aulanier G., Yelles Chaouche L., Nishizuka N., Harra L.K., Thalmann J.K., Vargas Dominguez S., Liu Y.
Projects: SDO-AIA,SDO-HMI
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Publication Status: A&A, in press
Last Modified: 2013-09-22 08:03
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Magnetohydrodynamic Modeling of the Solar Eruption on 2010 April 8
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Bernhard Kliem Submitted: 2014-07-11 09:00
The structure of the coronal magnetic field prior to eruptive processes and the conditions for the onset of eruption are important issues that can be addressed through studying the magnetohydrodynamic stability and evolution of nonlinear force-free field (NLFFF) models. This paper uses data-constrained NLFFF models of a solar active region that erupted on 2010 April 8 as initial condition in MHD simulations. These models, constructed with the techniques of flux rope insertion and magnetofrictional relaxation, include a stable, an approximately marginally stable, and an unstable configuration. The simulations confirm previous related results of magnetofrictional relaxation runs, in particular that stable flux rope equilibria represent key features of the observed pre-eruption coronal ... [READ MORE]
Authors: B. Kliem, Y. N. Su, A. A. van Ballegooijen, & E. E. DeLuca
Projects: Hinode/XRT,SDO-AIA,SDO-HMI,STEREO
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Publication Status: Published in ApJ 779, 129, 2013
Last Modified: 2014-07-11 14:34
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Magnetic Energy Partition between the CME and Flare from AR 11283
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Li Feng Submitted: 2013-01-16 07:04
On 6 September 2011, an X-class flare and a halo CME as observed from the
Earth were erupted from the same active region AR 11283. The magnetic energy
partition between them has been investigated. SDO/HMI vector magnetograms
were used to obtain the coronal magnetic field with the nonlinear force-free field
(NLFFF) extrapolation method. The free magnetic energies before and after
the flare were calculated to estimate the released energy available to power the
flare and the CME. For the flare energetics, thermal and nonthermal energies
were derived using the RHESSI and GOES data. To obtain the radiative output,
SDO/EVE data in the 0.1-37 nm waveband were utilized. We have reconstructed
the three dimensional (3D) periphery of the CME from the coronagraph images
observed by ... [READ MORE]
Authors: L. Feng, T. Wiegelmann, Y. Su, B. Inhester, Y.P. Li, X.D. Sun, W.Q. Gan
Projects: SDO-AIA,SDO-HMI,SDO-EVE,STEREO
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Publication Status: ApJ, in press
Last Modified: 2013-01-16 07:37
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X-ray precursors to flares and filament eruptions
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Cristina Chifor Submitted: 2007-07-03 03:49
Aims: To study preflare X-ray brightenings as diagnostics of the destabilisation of flare-associated erupting filaments/prominences.
<BR>
Methods: We combine new
observations from the Transition Region and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), as well as
revisit events reported in the literature to date, in order to scrutinise the preflare activity during eight flare-associated filament eruptions.
<BR>
Results: The preflare activity occurs in the form of
discrete, localised X-ray brightenings observed between 2 and 50 minutes before the impulsive phase of
the flare and filament acceleration. These transient preflare brightenings are situated on or
near (within 10'' of) the polarity inversion line (PIL), ... [READ MORE]
Authors: C. Chifor, D. Tripathi, H. E. Mason, B. R. Dennis
Projects: RHESSI,SoHO-EIT,SoHO-MDI,TRACE
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Publication Status: A&A, accepted, in press
Last Modified: 2007-07-03 09:43
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Observations of a Two-stage Solar Eruptive Event (SEE): Evidence for Secondary Heating
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Yang Su Submitted: 2013-01-17 09:06
We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event that occurred at the southwest limb on 2011 March 8. The GOES X-ray light curve shows two peaks separated by almost 2 hr that we interpret as two stages of a single event associated with the delayed eruption of a coronal mass ejection (CME). A hot flux rope formed during the first stage and continued expanding and rising throughout the event. The speed of the flux rope decreased from ~120 to 14 km s-1 during the decay phase of the first stage and increased again during the second stage to become the CME with a speed of ~516 km s-1. RHESSI and GOES data analyses show that the plasma temperature reached over 20 MK in the first stage, then decreased to ~10 MK and increased to 15 ... [READ MORE]
Authors: Su, Y.; Dennis, B. R.; Holman, G. D.; Wang, T. J.; Chamberlin, P. C.; Savage, S.; Veronig, A.
Projects: GOES X-rays ,SDO-AIA,SDO-EVE,SoHO-LASCO,STEREO
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Publication Status: ApJL, 746, L5, 2012
Last Modified: 2013-01-17 14:32
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Publication Status: 18 pages, 12 figures, 1 table, accepted for publication in ApJ
Last Modified: 2012-12-01 23:52
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Publication Status: accepted for publication in Solar Physics
Last Modified: 2019-05-08 09:52
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Publication Status: Accepted for publication in Astrophysical Journal
Last Modified: 2015-04-25 18:48
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Hard X-ray and ultraviolet emission during the 2011 June 7 solar flare
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Andrew Inglis Submitted: 2013-09-04 08:01
The relationship between X-ray and UV emission during flares, particularly in the context of quasi-periodic pulsations, remains unclear. To address this, we study the impulsive X-ray and UV emission during the eruptive flare of 2011 June 7 utilising X-ray imaging from RHESSI and UV 1700A imaging from SDO/AIA. This event is associated with quasi-periodic pulsations in X-ray and possibly UV emission, as well as substantial parallel and perpendicular motion of the hard X-ray footpoints.
The motion of the footpoints parallel to the flare ribbons is unusual; it is shown to reverse direction on at least two occasions. However, there is no associated short-timescale motion of the UV bright regions. Additionally, we find that the locations of the brightest X-ray and UV regions are different, ... [READ MORE]
Authors: A. R. Inglis, H. R. Gilbert
Projects: RHESSI,SDO-AIA,SDO-HMI
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Publication Status: ApJ, accepted
Last Modified: 2013-09-04 11:42
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Publication Status: accepted for publication in The Astrophysical Journal
Last Modified: 2013-06-12 13:52
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Publication Status: A&A, in press
Last Modified: 2016-09-07 12:12
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Publication Status: accepted for publication in A&A
Last Modified: 2012-05-22 08:56
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Publication Status: Adv. Space Res. (published online, in press)
Last Modified: 2015-03-25 08:16
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Publication Status: Accepted for publication in Astronomy and Astrophysics
Last Modified: 2007-08-14 07:35
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Publication Status: Accepted for publication in ApJ
Last Modified: 2019-07-20 21:30
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EIT and TRACE responses to flare plasma
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Durgesh Tripathi Submitted: 2006-11-06 09:38
Aims: To understand the contribution of active region and flare plasmas to the 195 A channels of SOHO/EIT (Extreme-ultraviolet Imaging Telescope) and TRACE (Transition Region and Coronal Explorer).
Methods: We have analysed an M8 flare simultaneously observed by the Coronal Diagnostic Spectrometer (CDS), EIT, TRACE and RHESSI. We obtained synthetic spectra for the flaring region and an outer region using the differential emission measures (DEM) of emitting plasma based on CDS and RHESSI observations and the CHIANTI atomic database. We then predicted the EIT and TRACE count rates.
Results: For the flaring region, both EIT and TRACE images taken through the 195 A filter are dominated by Fe XXIV (formed at about 20 MK). However, in the outer region, the emission was primarily due to ... [READ MORE]
Authors: D. Tripathi, G. Del Zanna, H. E. Mason, C. Chifor
Projects: SoHO-EIT,SoHO-CDS,TRACE
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Publication Status: Accepted for publication in A&A letters
Last Modified: 2006-11-06 09:46
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Validation of a Scaling Law for the Coronal Magnetic Field Strengths and Loop Lengths of Solar and Stellar Flares
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Kosuke Namekata Submitted: 2016-10-31 19:51
Shibata & Yokoyama (1999, 2002) proposed a method of estimating the coronal magnetic field strengths ($B$) and magnetic loop lengths ($L$) of solar and stellar flares, on the basis of magnetohydrodynamic simulations of the magnetic reconnection model. Using the scaling law provided by Shibata & Yokoyama (1999, 2002), $B$ and $L$ are obtained as functions of the emission measure ($EM=n^2L^3$) and temperature ($T$) at the flare peak. Here, $n$ is the coronal electron density of the flares. This scaling law enables the estimation of $B$ and $L$ for unresolved stellar flares from the observable physical quantities $EM$ and $T$, which is helpful for studying stellar surface activities. To apply this scaling law to stellar flares, we discuss its validity for spatially resolved solar flares. ... [READ MORE]
Authors: Kosuke Namekata, Takahito Sakaue, Kyoko Watanabe, Ayumi Asai, Kazunari Shibata
Projects: GOES X-rays,SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in PASJ
Last Modified: 2016-11-02 08:41
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Publication Status: Accepted for publication in the Astrophysical Journal
Last Modified: 2019-10-30 13:06
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Publication Status: 2012 ApJ, in press
Last Modified: 2012-08-08 12:14
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Multi-wavelength fine structure and mass flows in solar microflares
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Sigrid Berkebile-Stoiser Submitted: 2009-08-18 07:57
Aims. We study the multi-wavelength characteristics at high spatial resolution, as well as chromospheric evaporation signatures of solar microflares. To this end, we analyze the fine structure and mass flow dynamics in the chromosphere, transition region and corona of three homologous microflares (GOES class <A9/0.7 with/without background), which occurred on July 4, 2006 in AR 10898.
Methods. A multi-wavelength analysis using temporally and spatially highly resolved imaging data from the Dutch open telescope (H alpha, Ca II H), the transition region and coronal explorer (17.1 nm), the extreme-ultraviolet imaging telescope (19.5 nm), and the Reuven Ramaty high energy solar spectroscopic imager (>3 keV) was carried out. EUV line spectra provided by the coronal diagnostic ... [READ MORE]
Authors: Berkebile-Stoiser, S. ; G?m?ry, P.; Veronig, A.M.; Ryb?ak, J.; S?tterlin, P.
Projects: Dutch Open Telescope,RHESSI,SoHO-EIT,SoHO-MDI,SoHO-CDS,TRACE
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Publication Status: in press
Last Modified: 2009-08-18 08:39
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Publication Status: printed, DOI: 10.1051/0004-6361/201423471
Last Modified: 2014-05-07 06:01
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Publication Status: A&A (in press)
Last Modified: 2004-06-24 01:22
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Untwisting and Disintegration of a Solar Filament Associated with Photospheric Flux Cancellation
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Huadong Chen Submitted: 2018-12-19 02:27
Using the high-resolution observations from New Vacuum Solar Telescope (NVST) jointly with the Solar Dynamics Observatory data, we investigate two successive confined eruptions (Erup1 and Erup2) of a small filament in a decaying active region on 2017 November 10. During the process of Erup1, the overlying magnetic arcade is observed to inflate with the rising filament at beginning and then stop the ongoing of the explosion. In the hot EUV channel, a coronal sigmoidal structure appears during the first eruption and fade away after the second one. The untwisting rotation and disintegration of the filament in Erup2 are clearly revealed by the NVST Hα intensity data, hinting at a pre-existing twisted configuration of the filament. By tracking two rotating features in the filament, the ... [READ MORE]
Authors: Huadong Chen, Ruisheng Zheng, Leping Li, Suli Ma, Yi Bi, and Shuhong Yang
Projects: New Vacuum Solar Telescope (NVST),SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in the ApJ
Last Modified: 2018-12-19 12:30
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Publication Status: ApJL (accepted)
Last Modified: 2016-06-29 13:47
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Publication Status: in Proc. Coronal Heating, SOHO-15 Workshop, held in St.Andrews, UK, ed. ESA, ESTEC Noordwijk, The Netherlands, Special Publicati
Last Modified: 2004-10-01 14:57
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Observation of 2011-02-15 X2.2 flare in Hard X-ray and Microwave
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Natsuha Kuroda Submitted: 2015-06-04 22:48
Previous studies have shown that the energy release mechanism of some solar flares follow the Standard magnetic-reconnection model, but the detailed properties of high-energy electrons produced in the flare are still not well understood. We conducted a unique, multi-wavelength study that discloses the spatial, temporal and energy distributions of the accelerated electrons in the X2.2 solar flare on 2011, Feb. 15. We studied the source locations of seven distinct temporal peaks observed in hard X-ray (HXR) and microwave (MW) lightcurves using the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in 50 to 75 keV channels and Nobeyama Radioheliograph (NoRH) in 34 GHz, respectively. We found that the seven emission peaks did not come from seven spatially distinct sites in HXR and ... [READ MORE]
Authors: Natsuha Kuroda, Haimin Wang, Dale E. Gary
Projects: Nobeyama Radioheliograph,RHESSI,SDO-AIA,SDO-HMI
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Publication Status: ApJ (in press)
Last Modified: 2015-06-05 05:59
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Onset of a Large Ejective Solar Eruption from a Typical Coronal-Jet-Base Field Configuration
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Navin Chandra Joshi Submitted: 2017-07-04 22:04
Utilizing multiwavelength observations and magnetic field data from SDO/AIA, SDO/HMI, GOES and RHESSI, we investigate a large-scale ejective solar eruption of 2014 December 18 from active region NOAA 12241. This event produced a distinctive three-ribbon flare, having two parallel ribbons corresponding to the ribbons of a standard two-ribbon flare, and a larger-scale third quasi-circular ribbon offset from the other two ribbons. There are two components to this eruptive event. First, a flux rope forms above a strong-field polarity-inversion line and erupts and grows as the parallel ribbons turn on, grow, and spread part from that polarity-inversion line; this evolution is consistent with the tether-cutting-reconnection mechanism for eruptions. Second, the eruption of the arcade that has ... [READ MORE]
Authors: Navin Chandra Joshi, Alphonse C. Sterling, Ronald L. Moore, Tetsuya Magara, Young-Jae Moon
Projects: GOES X-rays,RHESSI,SDO-AIA,SDO-HMI,SoHO-LASCO
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Publication Status: Accepted for publication in ApJ Journal.
Last Modified: 2017-07-05 12:50
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Explosive events associated with a surge
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Maria Madjarska Submitted: 2009-06-10 07:54
The solar atmosphere contains a wide variety of small-scale transient features.
Here, we explore the inter-relation between some of them such as surges,
explosive events and blinkers via simultaneous spectral and imaging data taken
with the TRACE imager, the SUMER, and CDS spectrometers on board SoHO,
and SVST La Palma. The features were observed in spectral lines with formation
temperatures from 10,000 K to 1 MK and with the TRACE Fe ix/x 171 A
filter. The Halpha filtergrams were taken in the wings of the H 6365 A line at
?700 mA and ?350 mA. The alignment of all data both in time and solar XY
shows that SUMER line profiles, which are attributed to explosive events, are
due to a surge phenomenon. The surge?s up- and down-flows which often appear
simultaneously correspond to ... [READ MORE]
Authors: M.S. Madjarska, J.G. Doyle & B. de Pontieu
Projects: SoHO-SUMER,TRACE
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Publication Status: ApJ Part I, in press
Last Modified: 2009-06-10 09:19
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Publication Status: Accepted by ApJ
Last Modified: 2019-07-06 18:48
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The width distribution of solar coronal loops and strands - Are we hitting rock bottom ?
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Markus J Aschwanden Submitted: 2019-06-13 09:55
In this study, we analyze Atmospheric Imaging Assembly (AIA) and Hi-C images in order to investigate absolute limits for the finest loop strands. We develop a model of the occurrence-size distribution function of coronal loop widths, characterized by the lower limit of widths wmin, the peak (or most frequent) width w p, the peak occurrence number n p, and a power-law slope a. Our data analysis includes automated tracing of curvilinear features with the OCCULT-2 code, automated sampling of the cross-sectional widths of coronal loops, and fitting of the theoretical size distribution to the observed distribution. With Monte Carlo simulations and variable pixel sizes Δx, we derive a first diagnostic criterion to discriminate whether the loop widths are ... [READ MORE]
Authors: Aschwanden, M.J., Peter, H.
Projects: SDO-AIA
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Publication Status: ApJ 840:4 (24pp)
Last Modified: 2019-07-07 03:55
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Microflares and the Statistics of X-ray Flares
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Amir Caspi Submitted: 2011-10-28 12:21
This review surveys the statistics of solar X-ray flares, emphasising the new
views that RHESSI has given us of the weaker events (the microflares). The new
data reveal that these microflares strongly resemble more energetic events in
most respects; they occur solely within active regions and exhibit
high-temperature/nonthermal emissions in approximately the same proportion as
major events. We discuss the distributions of flare parameters (e.g., peak
flux) and how these parameters correlate, for instance via the Neupert effect.
We also highlight the systematic biases involved in intercomparing data
representing many decades of event magnitude. The intermittency of the
flare/microflare occurrence, both in space and in time, argues that these
discrete events do not explain general coronal ... [READ MORE]
Authors: I. G. Hannah, H. S. Hudson, M. Battaglia, S. Christe, J. Kasparova, S. Krucker, M. R. Kundu, A. Veronig
Projects: GONG,Hinode/EIS,Hinode/SOT,Hinode/XRT,Nobeyama Radioheliograph,Owens Valley Solar Array,RHESSI,SDO-AIA,SDO-HMI,SDO-EVE,SoHO-EIT,SoHO-MDI,SoHO-CDS,SoHO-LASCO,SoHO-SUMER,STEREO,TRACE
|
Publication Status: Published -- Hannah, I. G., et al. 2011, Space Sci. Rev., 159, 263; DOI 10.1007/s11214-010-9705-4
Last Modified: 2011-11-17 14:20
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SDO Observations of Magnetic Reconnection at Coronal Hole Boundaries
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Shuhong Yang Submitted: 2011-03-18 17:12
With the observations from the Atmospheric Imaging Assembly (AIA) and
the Helioseismic and
Magnetic Imager (HMI) aboard the Solar Dynamics Observatory, we
investigate the coronal hole
boundaries (CHBs) of an equatorial extension of polar coronal hole. At
the CHBs, lots of extreme-
ultraviolet (EUV) jets, which appear to be the signatures of magnetic
reconnection, are observed in the
193Å images, and some jets occur repetitively at the same sites. The
evolution of the jets is associated
with the emergence and cancelation of magnetic fields. We notice that
both the east and the west
CHBs shift westward, and the shift velocities are close to the
velocities of rigid rotation compared with
those of the photospheric differential rotation. This indicates that
magnetic reconnection ... [READ MORE]
Authors: Shuhong Yang, Jun Zhang, Ting Li, Yang Liu
Projects: SDO-AIA,SDO-HMI
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Publication Status: accepted for publication in ApJL
Last Modified: 2011-03-18 18:20
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Formation and Eruption of an Active Region Sigmoid. II. Magnetohydrodynamic Simulation of a Multistage Eruption
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Chaowei Jiang Submitted: 2018-10-30 21:05
Solar eruptions, mainly eruptive flares with coronal mass ejections, represent the most powerful drivers of space weather. Due to the low plasma-β nature of the solar corona, solar eruption has its roots in the evolution of the coronal magnetic field. Although various theoretical models of the eruptive magnetic evolution have been proposed, they still oversimplify the realistic process in observation, which shows a much more complex process due to the invisible complex magnetic environment. In this paper, we continue our study of a complex sigmoid eruption in solar active region 11283, which is characterized by a multipolar configuration embedding a null-point topology and a sigmoidal magnetic flux rope. Based on extreme ultraviolet observations, it has been suggested that a ... [READ MORE]
Authors: Chaowei Jiang, Xueshang Feng, and Qiang Hu
Projects: SDO-AIA,SDO-HMI
|
Publication Status: Published in ApJ
Last Modified: 2018-10-31 12:08
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Publication Status: accepted by apj
Last Modified: 2018-06-07 12:34
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Publication Status: Phys. Plasmas 20, 062903 (2013)
Last Modified: 2016-11-30 11:12
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2D Feature Recognition and 3D Reconstruction in Solar EUV Images
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Markus J. Aschwanden Submitted: 2005-01-31 18:38
EUV images show the solar corona in a typical temperature
range of T~1 MK, which encompasses the most common coronal
structures: loops, filaments, and other magnetic structures
in active regions, the quiet Sun, and coronal holes.
Quantitative analysis increasingly demands automated 2D feature
recognition and 3D reconstruction, in order to localize, track,
and monitor the evolution of such coronal structures.
We discuss numerical tools that ``fingerprint'' curvi-linear
1D features (e.g., loops and filaments). We discuss existing
finger-printing algorithms, such as the brightness gradient method,
the oriented-connectivity method, stereoscopic methods,
time-differencing, and space-time feature recognition.
We discuss improved 2D feature recognition and 3D ... [READ MORE]
Authors: Markus J. Aschwanden
Projects: Soho-EIT,Soho-MDI,Soho-CDS,Soho-LASCO,TRACE
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Publication Status: Solar Physics, (in press; accepted Feb 17, 2005)
Last Modified: 2005-02-17 12:43
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Large-scale Coronal Propagating Fronts in Solar Eruptions as Observed by the Atmospheric Imaging Assembly on Board the Solar Dynamics Observatory - An Ensemble Study
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Nariaki Nitta Submitted: 2013-08-18 21:49
This paper presents a study of a large sample of global disturbances in the solar corona with characteristic propagating fronts as intensity enhancement, similar to the phenomena that have often been referred to as EIT waves or EUV waves. Now Extreme Ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) provide a significantly improved view of these large-scale coronal propagating fronts (LCPFs). Between April 2010 and January 2013, a total of 171 LCPFs have been identified through visual inspection of AIA images in the 193 A channel. Here we focus on the 138 LCPFs that are seen to propagate across the solar disk, first studying how they are associated with flares, coronal mass ejections (CMEs) and type II radio bursts. ... [READ MORE]
Authors: Nitta, N. V., Schrijver, C. J., Title, A. M., Liu, W.
Projects: SDO-AIA
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Publication Status: Published, ApJ, 776, 58 (2013)
Last Modified: 2013-09-30 10:01
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Publication Status: In press, Solar Physics
Last Modified: 2019-07-21 23:47
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Publication Status: In Proceeding of SOHO 13, Mallorca of Spain, 2003; (invited), ESA SP-547, p.417
Last Modified: 2004-06-27 05:09
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Formation of a rotating jet during the filament eruption on 10-11 April 2013
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Boris Filippov Submitted: 2015-05-08 00:45
We analyze multi-wavelength and multi-viewpoint observations of a helically twisted plasma jet formed during a confined filament eruption on 10-11 April 2013. Given a rather large scale event with its high spatial and temporal resolution observations, it allows us to clearly understand some new physical details about the formation and triggering mechanism of twisting jet. We identify a pre-existing flux rope associated with a sinistral filament, which was observed several days before the event. The confined eruption of the filament within a null point topology, also known as an Eiffel tower (or inverted-Y) magnetic field
configuration results in the formation of a twisted jet after the magnetic reconnection near a null point. The sign of helicity in the jet is found to be the same as ... [READ MORE]
Authors: B. Filippov, A. K. Srivastava, B. N. Dwivedi, S. Masson, G. Aulanier, N. C. Joshi, and W. Uddin
Projects: SDO-AIA,STEREO
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Publication Status: Accepted for publication in MNRAS
Last Modified: 2015-05-12 14:02
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Publication Status: Accepted to CSCI-ISAI 2017, Las Vegas Conference
Last Modified: 2017-12-05 11:51
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Large-scale Coronal Propagating Fronts in Solar Eruptions as Observed by the Atmospheric Imaging Assembly on Board the Solar Dynamics Observatory - An Ensemble Study
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Nariaki Nitta Submitted: 2013-08-18 21:49
This paper presents a study of a large sample of global disturbances in the solar corona with characteristic propagating fronts as intensity enhancement, similar to the phenomena that have often been referred to as EIT waves or EUV waves. Now Extreme Ultraviolet (EUV) images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) provide a significantly improved view of these large-scale coronal propagating fronts (LCPFs). Between April 2010 and January 2013, a total of 171 LCPFs have been identified through visual inspection of AIA images in the 193 A channel. Here we focus on the 138 LCPFs that are seen to propagate across the solar disk, first studying how they are associated with flares, coronal mass ejections (CMEs) and type II radio bursts. ... [READ MORE]
Authors: Nitta, N. V., Schrijver, C. J., Title, A. M., Liu, W.
Projects: SDO-AIA
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Publication Status: Published as ApJ, 776, 58 (2013)
Last Modified: 2015-01-04 10:55
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The LYRA Instrument Onboard PROBA2: Description and In-Flight Performance
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Marie Dominique Submitted: 2013-02-26 11:26
The Large Yield Radiometer (LYRA) is an XUV-EUV-MUV (soft X-ray to
mid-ultraviolet) solar radiometer onboard the European Space Agency
PROBA2 mission that was launched in November 2009. LYRA acquires solar
irradiance measurements at a high cadence (nominally 20 Hz) in four
broad spectral channels, from soft X-ray to MUV, that have been chosen
for their relevance to solar physics, space weather and aeronomy. In
this article, we briefly review the design of the instrument, give an
overview of the data products distributed through the instrument
website, and describe the way that data are calibrated. We also
briefly present a summary of the main fields of research currently
under investigation by the LYRA consortium.
Authors: M. Dominique, J.-F. Hochedez, W. Schmutz, I.E. Dammasch, A.I. Shapiro, M. Kretzschmar, A.N. Zhukov, D. Gillotay, Y. Stockman, A. BenMoussa
Projects: PROBA2/LYRA
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Publication Status: Solar Physics (published)
Last Modified: 2013-02-26 15:39
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Publication Status: The Astrophysical Journal, Volume 833, Issue 1, article id. 5, 16 pp. (2016)
Last Modified: 2017-01-19 13:31
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The Eruption from a Sigmoidal Solar Active Region on 2005 May 13
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Chang Liu Submitted: 2007-07-15 12:57
This paper presents a multiwavelength study of the M8.0 flare and its associated fast halo CME that originated from a bipolar active region NOAA 10759 on 2005 May 13. The source active region has a conspicuous sigmoid structure at TRACE 171 A channel as well as in the SXI soft X-ray images, and we mainly concern ourselves with the detailed process of the sigmoid eruption as evidenced by the multiwavelength data ranging from Halpha, WL, EUV/UV, radio, and hard X-rays (HXRs). The most important finding is that the flare brightening starts in the core of the active region earlier than that of the rising motion of the flux rope. This timing clearly addresses one of the main issues in the magnetic eruption onset of sigmoid, namely, whether the eruption is initiated by an internal ... [READ MORE]
Authors: Chang Liu, Jeongwoo Lee, Vasyl Yurchyshyn, Na Deng, Kyung-Suk Cho, Marian Karlicky, and Haimin Wang
Projects: RHESSI,SoHO-EIT,SoHO-LASCO,TRACE
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Publication Status: The Astrophysical Journal, accepted July, 2007
Last Modified: 2007-07-15 15:48
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New Vacuum Solar Telescope observations of a flux rope tracked by a filament activation
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Shuhong Yang Submitted: 2014-03-04 20:07
One main goal of the New Vacuum Solar Telescope (NVST) which is located at the \emph{Fuxian Solar Observatory} is to image the Sun at high resolution. Based on the high spatial and temporal resolution NVST H_alpha data and combined with the simultaneous observations from the \emph{Solar Dynamics Observatory} for the first time, we investigate a flux rope tracked by a filament activation. The filament material is initially located at one end of the flux rope and fills in a section of the rope, and then the filament is activated due to magnetic field cancellation. The activated filament rises and flows along helical threads, tracking out the twisted flux rope structure. The length of the flux rope is about 75 Mm, the average width of its individual threads is 1.11 Mm, and the estimated ... [READ MORE]
Authors: Shuhong Yang, Jun Zhang, Zhong Liu, Yongyuan Xiang
Projects: Other,SDO-AIA,SDO-HMI
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Publication Status: Accepted for publication in ApJL
Last Modified: 2014-03-05 12:24
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Publication Status: Journal of Space Weather & Space Climate (in press)
Last Modified: 2015-06-15 10:45
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Publication Status: A&A
Last Modified: 2011-08-30 10:49
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Publication Status: accepted for publication in Solar Physics
Last Modified: 2016-01-20 12:25
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Publication Status: 14 pages,5 figures, ApJL (accepted)
Last Modified: 2013-05-13 10:03
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Publication Status: accepted by ApJL
Last Modified: 2019-10-18 09:50
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Multi-wavelength study of coronal waves associated with the CME-flare event of 03 November 2003
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Astrid Veronig Submitted: 2005-09-30 03:26
The large flare/CME event that occurred close to the west solar limb on 3 November 2003, launched a large-amplitude large-scale coronal wave which was imaged in H-alpha and Fe XII 195 A spectral lines, as well as in the soft X-ray and radio wavelength range. The wave excited also a complex decimeter-to-hectometer type II radio burst, revealing the formation of coronal shock(s). The back-extrapolation of the motion of coronal wave signatures and the type II burst sources distinctly marks the impulsive phase of the flare (the hard X-ray peak, drifting microwave burst, and the highest type III burst activity), favoring the flare-ignited wave scenario. On the other hand, the comparison of the kinematics of the CME expansion with the propagation of the optical wave signatures and type II burst ... [READ MORE]
Authors: B. Vrsnak, A. Warmuth, M. Temmer, A. Veronig, J. Magdalenic, A. Hillaris, M. Karlicky
Projects: RHESSI,Soho-EIT,Soho-MDI,Soho-LASCO
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Publication Status: A&A (in press)
Last Modified: 2005-09-30 03:26
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Deducing Electron Properties From Hard X-Ray Observations
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Amir Caspi Submitted: 2011-10-28 12:22
X-radiation from energetic electrons is the prime diagnostic of
flare-accelerated electrons. The observed X-ray flux (and polarization state)
is fundamentally a convolution of the cross-section for the hard X-ray emission
process(es) in question with the electron distribution function, which is in
turn a function of energy, direction, spatial location and time. To address the
problems of particle propagation and acceleration one needs to infer as much
information as possible on this electron distribution function, through a
deconvolution of this fundamental relationship. This review presents recent
progress toward this goal using spectroscopic, imaging and polarization
measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic
Imager (RHESSI). Previous conclusions ... [READ MORE]
Authors: E.P. Kontar, J.C. Brown, A.G. Emslie, W. Hajdas, G.D. Holman, G. J. Hurford, J. Kasparova, P. C. V. Mallik, A. M. Massone, M. L. McConnell, M. Piana, M. Prato, E. J. Schmahl, E. Suarez-Garcia
Projects: GONG,Hinode/EIS,Hinode/SOT,Hinode/XRT,Nobeyama Radioheliograph,Owens Valley Solar Array,RHESSI,SDO-AIA,SDO-HMI,SDO-EVE,SoHO-EIT,SoHO-MDI,SoHO-CDS,SoHO-LASCO,SoHO-SUMER,STEREO,TRACE
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Publication Status: Published -- Kontar, E. P., et al. 2011, Space Sci. Rev., 159, 301; DOI 10.1007/s11214-011-9804-x
Last Modified: 2011-11-17 14:20
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Motion magnification in coronal seismology
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Sergey Anfinogentov Submitted: 2016-11-08 03:15
We introduce a new method for the investigation of low-amplitude transverse oscillations of solar plasma non-uniformities, such as coronal loops, individual strands in coronal arcades, jets, prominence fibrils, polar plumes, and other contrast features, observed with imaging instruments. The method is based on the two-dimensional dual tree complex wavelet transform (DTCWT). It allows us to magnify transverse, in the plane-of-the-sky, quasi-periodic motions of contrast features in image sequences. The tests performed on the artificial data cubes imitating exponentially decaying, multi-periodic and frequency-modulated kink oscillations of coronal loops showed the effectiveness, reliability and robustness of this technique. The algorithm was found to give linear scaling of the magnified ... [READ MORE]
Authors: Sergey Anfinogentov and Valery M. Nakariakov
Projects: SDO-AIA
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Publication Status: Solar Physics (accepted)
Last Modified: 2016-11-09 08:47
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Direct Imaging by SDO/AIA of Quasi-periodic Propagating Fast Mode Magnetosonic Waves Propagating of ~2000 km/s in the Low Solar Corona
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Wei Liu Submitted: 2011-06-15 12:22
Quasi-periodic, propagating fast mode magnetosonic waves in the corona were
difficult to observe in the past due to relatively low instrument cadences. We
report here evidence of such waves directly imaged in EUV by the new SDO AIA
instrument. In the 2010 August 1 C3.2 flare/CME event, we find arc-shaped wave
trains of 1-5% intensity variations (lifetime ~200 s) that emanate near the
flare kernel and propagate outward up to ~400 Mm along a funnel of coronal
loops. Sinusoidal fits to a typical wave train indicate a phase velocity of
2200 +/- 130 km/s. Similar waves propagating in opposite directions are
observed in closed loops between two flare ribbons. In the k-$omega$ diagram
of the Fourier wave power, we find a bright ridge that represents the
dispersion relation and can be well ... [READ MORE]
Authors: Wei Liu, Alan M. Title, Junwei Zhao, Leon Ofman, Carolus J. Schrijver, Markus J. Aschwanden, Bart De Pontieu, and Theodore D. Tarbell
Projects: SDO-AIA
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Publication Status: Accepted by ApJ Letters (AAS/SPD Press Release, Las Cruces, June 15, http://www.lmsal.com/press/apjl2011_magnetosonic)
Last Modified: 2011-06-18 06:54
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Comparison of Five Numerical Codes for Automated Tracing of Coronal Loops
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Markus J. Aschwanden Submitted: 2007-05-21 13:11
The 3D modeling of coronal loops and filaments requires algorithms that
automatically trace curvi-linear features in solar EUV or soft X-ray
images. We compare 5 existing algorithms that have been developed and
customized to trace curvi-linear features in solar images:
(1) oriented-connectivity method (OCM), which is an extension of
the Strous pixel labeling algorithm
(developed by Lee, Newman, and Gary);
(2) dynamic aperture-based loop segmentation method
(developed by Lee, Newman, and Gary);
(3) unbiased detection of curvi-linear structures
(developed by Steger, Raghupathy, and Smith);
(4) oriented-direction method
(developed by Aschwanden); and
(5) ridge detection by automated scaling method
(developed by Inhester).
We test the 5 existing ... [READ MORE]
Authors: Markus Aschwanden, Jong Kwan Lee, G. Allen Gary, Mike Smith, & Bernd Inhester
Projects: TRACE
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Publication Status: submitted to Solar Physics for Topical Issue on Challenges in Solar Image Analysis and Visualization, presented at 3rd Solar Image Processing Workshop in Dublin, Ireland, 6-8 Sept 2006
Last Modified: 2007-05-22 08:55
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The GLE on Oct. 28, 2003 - radio diagnostics of relativistic electron and proton injection
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Henry Aurass Submitted: 2006-08-31 03:00
Timing discrepancies between signatures of accelerated particles at the sun and the arrival times of the particles at near-earth detectors are a matter of fundamental interest for space-weather applications. The solar injection times of various components of energetic particles were derived by Klassen et al. (2005) for the October 28, 2003, X-class / gamma-ray flare in NOAA AR10486. This flare occured in connection with a fast halo coronal mass ejection and a neutron monitor-observed ground level event (GLE). We used radio (Astrophysikalisches Institut Potsdam, WIND, Nancay Multifrequency Radio Heliograph), Halpha (Observatorium Kanzelhoehe), RHESSI, SOHO (EIT, LASCO, MDI), and TRACE data to study the associated chromospheric and low coronal phenomena. We identify three source sites of ... [READ MORE]
Authors: H. Aurass, G. Mann, G. Rausche, and A. Warmuth
Projects: RHESSI,SoHO-EIT,SoHO-MDI,TRACE
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Publication Status: A&A 2006 in press
Last Modified: 2006-08-31 10:17
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Comparison between Hinode/SOT and SDO/HMI, AIA Data for the Study of the Solar Flare Trigger Process
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Yumi Bamba Submitted: 2014-07-07 11:06
Understanding the mechanism that produces solar flares is important not only from the scientific point of view but also for improving space weather predictability. There are numerous observational and computational studies, which attempted to reveal the onset mechanism of solar flares. However, the underlying mechanism of flare onset remains elusive. To elucidate the flare trigger mechanism, we have analyzed several flare events which were observed by Hinode/Solar Optical Telescope (SOT), in our previous study. Because of the limitation of SOT field of view, however, only four events in the Hinode data sets have been utilizable. Therefore, increasing the number of events is required for evaluating the flare trigger models.
We investigated the applicability of data obtained by the ... [READ MORE]
Authors: Yumi Bamba, Kanya Kusano, Shinsuke Imada, Yusuke Iida
Projects: Hinode/SOT,SDO-AIA,SDO-HMI
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Publication Status: Accepted to PASJ, Hinode special issue
Last Modified: 2014-07-09 13:41
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On the Performance of Multi-Instrument Solar Flare Observations During Solar Cycle 24
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Ryan Milligan Submitted: 2017-03-14 04:08
The current fleet of space-based solar observatories offers us a wealth of opportunities to study solar flares over a range of wavelengths. Significant advances in our understanding of flare physics often come from coordinated observations between multiple instruments. Consequently, considerable efforts have been, and continue to be made to coordinate observations among instruments (e.g. through the Max Millennium Program of Solar Flare Research). However, there has been no study to date that quantifies how many flares have been observed by combinations of various instruments. Here we describe a technique that retrospectively searches archival databases for flares jointly observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Solar Dynamics Observatory (SDO)/EUV ... [READ MORE]
Authors: Ryan Milligan, Jack Ireland
Projects: GOES/EUVS,GOES X-rays,Hinode/EIS,Hinode/SOT,Hinode/XRT,IRIS,PROBA2/SWAP,RHESSI,SDO-EVE
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Publication Status: 26 pages, 7 figures, 3 tables. Accepted in Solar Physics
Last Modified: 2018-01-09 11:31
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Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares
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James McLaughlin Submitted: 2018-02-13 04:15
Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic pulsations (QPPs), to emphasise that they often contain apparent amplitude and period modulation. We review the current understanding of quasi-periodic pulsations in solar and stellar flares. In particular, we focus on the possible physical mechanisms, with an emphasis on the underlying physics that generates the resultant range of periodicities. These physical mechanisms include MHD oscillations, self-oscillatory mechanisms, oscillatory ... [READ MORE]
Authors: McLaughlin, J.A., Nakariakov, V.M., Dominique, M., Jel?nek, P., Takasao, S.
Projects: Fermi/GBM,GOES X-rays,Nobeyama Radioheliograph,Other,PROBA2/LYRA,RHESSI
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Publication Status: [published] 2018, Space Science Reviews, 214, 45
Last Modified: 2018-02-14 11:41
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Kinematics of ICMEs/Shocks: Blast Wave Reconstruction Using Type-II Emissions
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