E-Print Archive

There are 4451 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
High resolution observations with Artemis-IV and the NRH. I. Type IV associated narrow-band bursts View all abstracts by submitter

Alexander Hillaris   Submitted: 2019-06-10 06:29

Context. Narrow-band bursts appear on dynamic spectra from microwave to decametric frequencies as fine structures with very small duration and bandwidth. They are believed to be manifestations of small scale energy release through magnetic reconnection. Aims: We analyzed 27 metric type IV events with embedded narrow-band bursts, which were observed by the ARTEMIS-IV radio spectrograph from 30 June 1999 to 1 August 2010. We examined the morphological characteristics of isolated narrow-band structures (mostly spikes) and groups or chains of structures. Methods: The events were recorded with the SAO high resolution (10 ms cadence) receiver of ARTEMIS-IV in the 270-450 MHz range. We measured the duration, spectral width, and frequency drift of ~12 000 individual narrow-band bursts, groups, and chains. Spike sources were imaged with the Nançay radioheliograph (NRH) for the event of 21 April 2003. Results: The mean duration of individual bursts at fixed frequency was ~100 ms, while the instantaneous relative bandwidth was ~2%. Some bursts had measurable frequency drift, either positive or negative. Quite often spikes appeared in chains, which were closely spaced in time (column chains) or in frequency (row chains). Column chains had frequency drifts similar to type-IIId bursts, while most of the row chains exhibited negative frequently drifts with a rate close to that of fiber bursts. From the analysis of NRH data, we found that spikes were superimposed on a larger, slowly varying, background component. They were polarized in the same sense as the background source, with a slightly higher degree of polarization of ~65%, and their size was about 60% of their size in total intensity. Conclusions: The duration and bandwidth distributions did not show any clear separation in groups. Some chains tended to assume the form of zebra, lace stripes, fiber bursts, or bursts of the type-III family, suggesting that such bursts might be resolved in spikes when viewed with high resolution. The NRH data indicate that the spikes are not fluctuations of the background, but represent additional emission such as what would be expected from small-scale reconnection.

Authors: C. Bouratzis, A. Hillaris, C.E. Alissandrakis, P. Preka-Papadema, X. Moussas, C. Caroubalos, P. Tsitsipis, A. Kontogeorgos
Projects: None

Publication Status: Astronomy & Astrophysics, Volume 586, id.A29, 11 pp.
Last Modified: 2019-06-12 12:19
Go to main E-Print page  Interplanetary Type IV Bursts  Detection of spike-like structures near the front of type-II burstsA  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

Key
Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
Structural evolution of a magnetic flux rope associated with a major flare in the solar active region 12205
Homologous Coronal Mass Ejections Caused by Recurring Formation and Disruption of Current Sheet within a Sheared Magnetic Arcade
Propagating Oscillations in the Lower Atmosphere Under Coronal Holes
Using Flare-Induced Modulation of Three- and Five-Minute Oscillations for Studying Wave Propagation in the Solar Atmosphere
Plasma dynamics in the flaring loop observed by RHESSI
Multi-instrument STIX microflare study
Disambiguation of Vector Magnetograms by Stereoscopic Observations from the Solar Orbiter/Polarimetric and Helioseismic Imager (PHI) and the Solar Dynamic Observatory (SDO)/Helioseismic and Magnetic Imager (HMI)
Enhanced Phase Mixing of Torsional Alfvén Waves in Stratified and Divergent Solar Coronal Structures, Paper II: Nonlinear Simulations
Multi-Passband Observations of A Solar Flare over the He I 10830 line
Multi-wavelength quasi-periodic pulsations in a stellar superflare
Probable detection of an eruptive filament from a superflare on a solar-type star
Global Energetics in Solar Flares. XIII. The Neupert Effect and Acceleration of Coronal Mass Ejections
Enhanced Phase Mixing of Torsional Alfvén Waves in Stratified and Divergent Solar Coronal Structures, Paper I: Linear Solutions
Variations of the Internal Asymmetries of Sunspot Groups During their Decay
Partial Eruption, Confinement, and Twist Buildup and Release of a Double-decker Filament
Overdense Threads in the Solar Corona Induced by Torsional Alfvén Waves
Implications of spicule activity on coronal loop heating and catastrophic cooling
The Magnetic Origin of Solar Campfires
On the evolution of a sub-C class flare: a showcase for the capabilities of the revamped Catania Solar Telescope
Direct evidence that twisted flux tube emergence creates solar active regions

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



© 2000-2020 Solar Physics Group - Montana State University