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Solar flares are sudden energy release events in the solar corona, resulting from magnetic reconnection, that accelerates particles and heats the ambient plasma. During a flare, there are often multiple, temporally and spatially separated…

Solar and Stellar Astrophysics · Physics 2020-12-02 Rohit Sharma , Marina Battaglia , Yingjie Luo , Bin Chen , Sijie Yu

Solar flare hard X-ray spectra from RHESSI are normally interpreted in terms of purely collisional electron beam propagation, ignoring spatial evolution and collective effects. In this paper we present self-consistent numerical simulations…

Solar and Stellar Astrophysics · Physics 2014-11-20 I. G. Hannah , E. P. Kontar , O. K. Sirenko

We propose a new two-stage model for acceleration of electrons in solar flares. In the first stage, electrons are accelerated stochastically in a post-reconnection turbulent downflow. The second stage is the reprocessing of a subset of…

Astrophysics · Physics 2008-11-26 Robert Selkowitz , Eric G. Blackman

All stars produce explosive surface events such as flares and coronal mass ejections. These events are driven by the release of energy stored in coronal magnetic fields, generated by the stellar dynamo. However, it remains unclear if the…

To solve a number of problems in solar physics related to mechanisms of energy release in solar corona parameters of hot coronal plasma are required, such as energy distribution, emission measure, differential emission measure, and their…

Solar and Stellar Astrophysics · Physics 2015-10-26 G. G. Motorina , E. P. Kontar

During solar flares, a large flux of energetic electrons propagate from the tops of reconnecting magnetic flux tubes toward the lower atmosphere. Over the course of the electrons' transport, a co-spatial counter-streaming return current is…

Solar and Stellar Astrophysics · Physics 2021-08-25 Meriem Alaoui , Gordon D. Holman , Joel C. Allred , Rafael T. Eufrasio

We examine effects on the charge states of energetic ions associated with gradual solar flares due to shock heating and stripping at high ion velocities. Recent measurements of the mean charges of various elements after the flares of 1992…

Astrophysics · Physics 2009-10-30 D. Ruffolo

The hard X-ray (HXR) emission in solar flares comes almost exclusively from a very small part of the flaring region, the footpoints of magnetic loops. Using RHESSI observations of solar flare footpoints, we determine the radial positions…

Solar and Stellar Astrophysics · Physics 2015-05-27 Marina Battaglia , Eduard P. Kontar

Recurrent, arc-shaped intensity disturbances were detected by EUV channels in an active region. The fronts were observed to propagate along a coronal loop bundle rooted in a small area within a sunspot umbra. Previous works have linked…

Solar and Stellar Astrophysics · Physics 2022-11-02 M. V. Sieyra , S. Krishna Prasad , G. Stenborg , E. Khomenko , T. Van Doorsselaere , A. Costa , A. Esquivel , J. M. Riedl

We study the relationship between implosive motions in a solar flare, and the energy redistribution in the form of oscillatory structures and particle acceleration. The flare SOL2012-03-09T03:53 (M6.4) shows clear evidence for an…

Solar and Stellar Astrophysics · Physics 2015-06-17 P. J. A. Simões , L. Fletcher , H. S. Hudson , A. J. B. Russell

During solar flares fast electron beams generated in the solar corona are non-thermal radio sources in terms of type III bursts. Sometimes they can enter into the interplanetary space, where they can be observed by in-situ measurements as…

Solar and Stellar Astrophysics · Physics 2011-12-23 H. Önel , G. Mann , E. Sedlmayr

Results from the Solar Maximum Mission showed a close connection between the hard X-ray and transition region emission in solar flares. Analogously, the modern combination of RHESSI and IRIS data can inform the details of heating processes…

Solar and Stellar Astrophysics · Physics 2016-08-31 Jeffrey W. Reep , Harry P. Warren , Nicholas A. Crump , Paulo J. A. Simoes

We analyse the observational characteristics for a set of Long Duration Events (LDE) using Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Excellent energy resolution (1 keV) of HXR images reconstructed with RHESSI allowed us…

Solar and Stellar Astrophysics · Physics 2015-03-19 Tomasz Mrozek , Zbigniew Koltun , Sylwester Kolomanski , Urszula Bak-Steslicka

During a solar flare, electrons are accelerated to non-thermal energies as a result of magnetic reconnection. These electrons then propagate upwards and downwards from the energy release site along magnetic field lines and produce radio and…

Solar and Stellar Astrophysics · Physics 2025-03-04 Shilpi Bhunia , Laura A. Hayes , Karl Ludwig Klein , Nicole Vilmer , Shane A. Maloney , Peter T. Gallagher

Even small solar flares can display a surprising level of complexity regarding their morphology and temporal evolution. Many of their properties, such as energy release and electron acceleration can be studied using highly complementary…

Solar and Stellar Astrophysics · Physics 2021-12-08 Marina Battaglia , Rohit Sharma , Yingjie Luo , Bin Chen , Sijie Yu , Säm Krucker

Energetic particle populations in the solar corona and in the heliosphere appear to have different characteristics even when produced in the same solar flare. It is not clear what causes this difference: properties of the acceleration…

Solar and Stellar Astrophysics · Physics 2023-07-26 Mykola Gordovskyy , Philippa K. Browning , Kanya Kusano , Satoshi Inoue , Gregory E. Vekstein

Energetic electrons accelerated at coronal reconnection sites during solar flares precipitate into the lower solar atmosphere, generating nonthermal emissions and regulating energy deposition. However, how their transport and precipitation…

Solar and Stellar Astrophysics · Physics 2026-05-07 Feiyu Yu , Xiangliang Kong , Ze Zhong , Zhentong Li , Zelong Jiang , Yingli Cui , Zhao Wu , Yao Chen , Gang Li

In order to study the acceleration and propagation of bremsstrahlung-producing electrons in solar flares, we analyze the evolution of the flare loop size with respect to energy at a variety of times. A GOES M3.7 loop-structured flare…

Solar and Stellar Astrophysics · Physics 2015-06-05 Jingnan Guo , A. Gordon Emslie , Eduard P. Kontar , Federico Benvenuto , Anna Maria Massone , Michele Piana

We report observations of white-light ejecta in the low corona, for two X-class flares on the 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources…

The content of hot material in the corona is not constant. Soft X-ray and high-temperature EUV line observations show that new material, apparently heated and evaporated from the chromosphere, is frequently injected into the corona both in…

Astrophysics · Physics 2016-08-30 Arnold O. Benz , Paolo C. Grigis