E-Print Archive

There are 3914 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
Helium abundance and speed difference between helium ions and protons in the solar wind from coronal holes, active regions, and quiet Sun  

Maria Madjarska   Submitted: 2018-05-14 05:36

Two main models have been developed to explain the mechanisms of release, heating and acceleration of the nascent solar wind, the wave-turbulence-driven (WTD) models and reconnection-loop-opening (RLO) models, in which the plasma release processes are fundamentally different. Given that the statistical observational properties of helium ions produced in magnetically diverse solar regions could provide valuable information for the solar wind modelling, we examine the statistical properties of the helium abundance (AHe) and the speed difference between helium ions and protons (vαp) for coronal holes (CHs), active regions (ARs) and the quiet Sun (QS). We find bimodal distributions in the space of AHe and vαp/vA (where vA is the local Alfvén speed)for the solar wind as a whole. The CH wind measurements are concentrated at higher AHe and vαp/vA values with a smaller AHe distribution range, while the AR and QS wind is associated with lower AHe and vαp/vA, and a larger AHe distribution range. The magnetic diversity of the source regions and the physical processes related to it are possibly responsible for the different properties of AHe and vαp/vA. The statistical results suggest that the two solar wind generation mechanisms, WTD and RLO, work in parallel in all solar wind source regions. In CH regions WTD plays a major role, whereas the RLO mechanism is more important in AR and QS.

Authors: Fu, Hui, Madjarska, Maria S., Li, Bo, Xia, LiDong, Huang, ZhengHua
Projects: SDO-AIA,SDO-HMI

Publication Status: in press in MNRS
Last Modified: 2018-05-14 10:46
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Plasma parameters and geometry of cool and warm active region loops  

Maria Madjarska   Submitted: 2017-05-09 16:57

How the solar corona is heated to high temperatures remains an unsolved mystery in solar physics. In the present study we analyse observations of 50 whole active-region loops taken with the Extreme-ultraviolet Imaging Spectrometer (EIS) on board the Hinode satellite. Eleven loops were classified as cool (<1 MK) and 39 as warm (1-2 MK) loops. We study their plasma parameters such as densities, temperatures, filling factors, non-thermal velocities and Doppler velocities. We combine spectroscopic analysis with linear force-free magnetic-field extrapolation to derive the three-dimensional structure and positioning of the loops, their lengths and heights as well as the magnetic field strength along the loops. We use density-sensitive line pairs from Fe XII, Fe XIII, Si X and Mg VII ions to obtain electron densities by taking special care of intensity background-subtraction. The emission-measure loci method is used to obtain the loop temperatures. We find that the loops are nearly isothermal along the line-of-sight. Their filling factors are between 8% and 89%. We also compare the observed parameters with the theoretical RTV scaling law. We find that most of the loops are in an overpressure state relative to the RTV predictions. In a followup study, we will report a heating model of a parallel-cascade-based mechanism and will compare the model parameters with the loop plasma and structural parameters derived here.

Authors: Haixia Xie, Maria S. Madjarska, Bo Li, Zhenghua Huang, Lidong Xia, Thomas Wiegelmann, Hui Fu, Chaozhou Mou
Projects: Hinode/EIS

Publication Status: ApJ, accepted for publication
Last Modified: 2017-05-10 09:18
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Charge states and FIP bias of the solar wind from coronal holes, active regions, and quiet Sun  

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-1 and a fast at ~600 km s-1. 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 NFe/NO range and its average values all decrease with the increasing solar wind speed in different types of solar wind. The NFe/NO range (0.06-0.40, FIP boas range 1-7) for AR wind is wider than for CH wind (0.06-0.20, FIP boas range 1-3) while the minimum value of NFe/NO (~0.06) does not change with the variation of speed, and it is similar for all source regions. The two-peak distribution of CH wind and the anti-correlation between the speed and O7+/O6+ in all three types of solar wind can be explained qualitatively by both the wave-turbulence-driven (WTD) and reconnection-loop-opening (RLO) models, whereas the distribution features of NFe/NO in different source regions of solar wind can be explained more reasonably by the RLO models.

Authors: Hui Fu, Maria S. Madjarska, LiDong Xia, Bo Li, ZhengHua Huang, Zhipeng Wangguan
Projects: ACE,SoHO-EIT,SoHO-MDI

Publication Status: accepted for publication in ApJ
Last Modified: 2017-01-31 11:46
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Coronal hole boundaries at small scales: III. EIS and SUMER views  

Maria Madjarska   Submitted: 2012-07-03 03:43

We report on the plasma properties of small-scale transient events identified in the quiet Sun, coronal holes and their boundaries. We aim at deriving the physical characteristics of events which were identified as small-scale transient brightenings in XRT images. We use spectroscopic co-observations from SUMER/SoHO and EIS/Hinode combined with high cadence imaging data from XRT/Hinode. We measure Doppler shifts using single and multiple Gauss fits of transition region and coronal lines as well as electron densities and temperatures. We combine co-temporal imaging and spectroscopy to separate brightening expansions from plasma flows. The transient brightening events in coronal holes and their boundaries were found to be very dynamical producing high density outflows at large speeds. Most of these events represent X-ray jets from pre-existing or newly emerging coronal bright points at X-ray temperatures. The average electron density of the jets is log10Ne ≈8.76 cm-3 while in the flaring site it is log10Ne ≈9.51 cm-3. The jet temperatures reach a maximum of 2.5 MK but in the majority of the cases the temperatures do not exceed 1.6 MK. The footpoints of jets have temperatures of a maximum of 2.5 MK though in a single event scanned a minute after the flaring the measured temperature was 12 MK. The jets are produced by multiple microflaring in the transition region and corona. Chromospheric emission was only detected in their footpoints and was only associated with downflows. The Doppler shift measurements in the quiet Sun transient brightenings confirmed that these events do not produce jet-like phenomena. The plasma flows in these phenomena remain trapped in closed loops. We can conclude that the dynamic day-by-day and even hour-by-hour small-scale evolution of coronal hole boundaries reported in paper I is indeed related to coronal bright points. The XRT observations reported in paper II revealed that these changes are associated with the dynamic evolution of coronal bright points producing multiple jets during their lifetime until their full disappearance. We demonstrated here through spectroscopic EIS and SUMER co-observations combined with high-cadence imaging information that the co-existence of open and closed magnetic fields results in multiple energy depositions which propel high density plasma along open magnetic field lines. We conclude from the physical characteristics obtained in this study that X-ray jets are an important candidate for the source of the slow solar wind. This, however, does not exclude the possibility that these jets are also the microstreams observed in the fast solar wind as recently suggested.

Authors: M.S. Madjarska, Z. Huang, J.G. Doyle and S. Subramanian
Projects: SoHO-SUMER

Publication Status: accepted for publication in A&A
Last Modified: 2012-07-03 10:47
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Kinematics and helicity evolution of a loop-like eruptive prominence  

Maria Madjarska   Submitted: 2012-02-13 06:50

Aims. We aim at investigating the morphology, kinematic and helicityevolution of a loop-like prominence during itseruption.
Methods. We use multi-instrument observations from AIA/SDO,EUVI/STEREO and LASCO/SoHO. The kinematic,morphological, geometrical, and helicity evolution of a loop-likeeruptive prominence are studied in the context of themagnetic flux rope model of solar prominences.
Results. The prominence eruption evolved as a height expanding twistedloop with both legs anchored in the chromo-sphere of a plage area. The eruption process consists of a prominenceactivation, acceleration, and a phase of constantvelocity. The prominence body was composed of left-hand(counter-clockwise) twisted threads around the main promi-nence axis. The twist during the eruption was estimated at 6π (3 turns). The prominence reached a maximum height of 526 Mm before contracting to its primary location and partiallyreformed in the same place two days after the eruption.This ejection, however, triggered a CME seen in LASCO C2. Theprominence was located in the northern periphery ofthe CME magnetic field configuration and, therefore, the backgroundmagnetic field was asymmetric with respect tothe filament position. The physical conditions of the falling plasmablobs were analysed with respect to the prominencekinematics.
Conclusions. The same sign of the prominence body twist and writhe, aswell as the amount of twisting above the criticalvalue of 2π after the activation phase indicate that possibly conditions for kinkinstability were present. No signature ofmagnetic reconnection was observed anywhere in the prominence body andits surroundings. The filament/prominencedescent following the eruption and its partial reformation at the sameplace two days later suggest a confined type oferuption. The asymmetric background magnetic field possibly played animportant role in the failed eruption.

Authors: K. Koleva, M.S. Madjarska, P. Duchlev, C. J. Schrijver, J.-C. Vial, E. Buchlin, and M. Dechev
Projects: SDO-AIA,SoHO-LASCO

Publication Status: accepted for publication in A&A
Last Modified: 2012-02-14 12:12
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

What is the true nature of blinkers  

Maria Madjarska   Submitted: 2011-11-07 07:03

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: S. Subramanian, M. S. Madjarska, J. G. Doyle and D. Bewsher
Projects: Hinode/EIS,Hinode/SOT,Hinode/XRT,SoHO-CDS,STEREO

Publication Status: in press in A&A
Last Modified: 2011-11-07 10:47
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Can coronal hole spicules reach coronal temperatures?  

Maria Madjarska   Submitted: 2011-05-06 09:51

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: M.S. Madjarska, K. Vanninathan and J.G. Doyle
Projects: Hinode/EIS,Hinode/SOT,SoHO-SUMER

Publication Status: accepted in A&A
Last Modified: 2011-05-06 17:07
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Explosive events associated with a surge  

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 Å filter. The Hα 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 the blue- and red-shifted emission of the transition region N V 1238.82 A and O V 629.77 A lines as well as radiance increases of the C I, S I and S II and Si II chromospheric lines. Some parts of the surge are also visible in the TRACE 171 Å images which could suggest heating to coronal temperatures. The surge is triggered, most probably, by one or more Elerman bombs which are best visible in H ?350 A but were also registered by TRACE Fe IX/X 171 Å and correspond to a strong radiance increase in the CDS Mg IX 368.07 A line. With the present study we demonstrate that the division of small-scale transient events into a number of different subgroups, for instance explosive events, blinkers, spicules, surges or just brightenings, is ambiguous, implying that the definition of a feature based only on either spectroscopic or imaging characteristics as well as insufficient spectral and spatial resolution can be incomplete.

Authors: M.S. Madjarska, J.G. Doyle & B. de Pontieu
Projects: SoHO-SUMER,TRACE

Publication Status: ApJ Part I, in press
Last Modified: 2009-06-10 09:19
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Coronal hole boundaries evolution at small scales: I. EIT 195 A and TRACE 171 Å view  

Maria Madjarska   Submitted: 2009-06-10 07:52

Aims. We aim at studying the small-scale evolution at the boundaries of an equatorial coronal hole connected with a channel of open magnetic flux with the polar region and an "isolated" one in the extreme-ultraviolet spectral range. We intend to determine the spatial and temporal scale of these changes. Methods. Imager data from TRACE in the Fe IX/X 171 Å passband and EIT on-board Solar and Heliospheric Observatory in the Fe XII 195 A passband were analysed. Results. We found that small-scale loops known as bright points play an essential role in coronal holes boundaries evolution at small scales. Their emergence and disappearance continuously expand or contract coronal holes. The changes appear to be random on a time scale comparable with the lifetime of the loops seen at these temperatures. No signature was found for a major energy release during the evolution of the loops. Conclusions. Although coronal holes seem to maintain their general shape during a few solar rotations, a closer look at their day-by-day and even hour-by-hour evolution demonstrates a significant dynamics. The small-scale loops (10''?40'' and smaller) which are abundant along coronal hole boundaries have a contribution to the small-scale evolution of coronal holes. Continuous magnetic reconnection of the open magnetic field lines of the coronal hole and the closed field lines of the loops in the quiet Sun is more likely to take place.

Authors: M.S. Madjarska & T. Wiegelmann
Projects: SoHO-EIT,TRACE

Publication Status: A&A, in press
Last Modified: 2009-06-12 09:09
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 


Key
Go to main E-Print pageGo to main E-Print page.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
Delete AbstractDelete abstract.

Abstracts by Author
Helium abundance and speed difference between helium ions and protons in the solar wind from coronal holes, active regions, and quiet Sun
Plasma parameters and geometry of cool and warm active region loops
Charge states and FIP bias of the solar wind from coronal holes, active regions, and quiet Sun
Coronal hole boundaries at small scales: III. EIS and SUMER views
Kinematics and helicity evolution of a loop-like eruptive prominence
What is the true nature of blinkers
Can coronal hole spicules reach coronal temperatures?
Explosive events associated with a surge
Coronal hole boundaries evolution at small scales: I. EIT 195 A and TRACE 171 A view

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2003 Solar Physics Group - Montana State University