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We investigate the acceleration and transport of electrons in the highly fine-structured current sheet that develops during magnetic flux rope (MFR) eruptions. Our work combines ultra-resolved MHD simulations of MFR eruption, with…

Solar and Stellar Astrophysics · Physics 2025-09-29 Hao Wu , Yang Guo , Rony Keppens , Chun Xia , Yang Su , Xiangliang Kong , Mingde Ding

The first self-consistent simulations of electron acceleration during magnetic reconnection in a macroscale system are presented. Consistent with solar flare observations the spectra of energetic electrons take the form of power-laws that…

Within the framework of a two-fluid description possible pathways for the generation of fast flows (dynamical as well as steady) in the lower solar atmosphere is established. It is shown that a primary plasma flow (locally sub-Alfv\'enic)…

Our aim is to evaluate the maximum attainable energies of electrons accelerated by means of the magneto-centrifugal mechanism. We examine how the range of maximum possible energies, as well as the primary limiting factors, vary with black…

High Energy Astrophysical Phenomena · Physics 2025-07-29 N. Nikuradze , Z. N. Osmanov

Solar flares - the most powerful explosions in the solar system - are also efficient particle accelerators, capable of energizing a large number of charged particles to relativistic speeds. A termination shock is often invoked in the…

Solar and Stellar Astrophysics · Physics 2015-12-09 Bin Chen , Timothy S. Bastian , Chengcai Shen , Dale E. Gary , Sam Krucker , Lindsay Glesener

The two-temperature relativistic electron spectrum from a low-density ($3\times10^{17}$~cm$^{-3}$) self-modulated laser wakefield accelerator (SM-LWFA) is observed to transition between temperatures of $19\pm0.65$ and $46\pm2.45$ MeV at an…

A number of double coronal X-ray sources have been observed during solar flares by RHESSI, where the two sources reside at different sides of the inferred reconnection site. However, where and how are these X-ray-emitting electrons…

Solar and Stellar Astrophysics · Physics 2022-07-20 Xiangliang Kong , Jing Ye , Bin Chen , Fan Guo , Chengcai Shen , Xiaocan Li , Sijie Yu , Yao Chen , Joe Giacalone

Blazars are known to emit a broad band emission from radio to gamma-rays with rapid time variations, particularly, in X- and gamma-rays. Synchrotron radiation and inverse Compton scattering are thought to play an important role in emission…

Astrophysics · Physics 2009-10-31 M. Kusunose , F. Takahara , H. Li

Using a model of particle acceleration and transport in solar flares, we investigate the height distribution of coronal electrons by focusing on the energy-dependent pitch-angle scattering. When pitch-angle scattering is not included, the…

Solar and Stellar Astrophysics · Physics 2015-05-27 Takashi Minoshima , Satoshi Masuda , Yoshizumi Miyoshi , Kanya Kusano

We propose that non-thermal electrons are efficiently accelerated by first-order Fermi process at the fast shock, as a natural consequence of the new magnetohydrodynamic picture of the flaring region revealed with Yohkoh. An oblique fast…

Astrophysics · Physics 2009-10-30 Saku Tsuneta , Tsuguya Naito

The direct current (DC) electric field near the reconnection region has been proposed as an effective mechanism to accelerate protons and electrons in solar flares. A power-law energy spectrum was generally claimed in the simulations of…

Astrophysics · Physics 2011-02-11 W. J. Liu , P. F. Chen , M. D. Ding , C. Fang

This paper reviews the current state of our understanding of high-speed solar wind acceleration in coronal holes. Observations by SOHO, coupled with interplanetary particle measurements going back several decades, have put strong…

Astrophysics · Physics 2007-05-23 Steven R. Cranmer

In large gradual solar energetic particle (SEP) events, especially the ground-level enhancement (GLE) events, where and how energetic particles are accelerated is still a problem. By using imaging data from TRACE, Yohkoh/HXT, SOHO/MDI and…

Astrophysics · Physics 2008-11-26 C. Li , Y. H. Tang , Y. Dai , W. G. Zong , C. Fang

Using 2D particle-in-cell (PIC) plasma simulations we study electron acceleration by temperature anisotropy instabilities, assuming conditions typical of above-the-loop-top (ALT) sources in solar flares. We focus on the long-term effect of…

Solar and Stellar Astrophysics · Physics 2022-01-19 Mario Riquelme , Alvaro Osorio , Daniel Verscharen , Lorenzo Sironi

The extreme solar and SEP event of 20 January 2005 is analyzed from two perspectives. Firstly, we study features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly,…

This Research Note is in response to the recent paper by S. M. Perriyil et al. (2026). They provide measurements of the time delay (delta t) between the hard X-ray and soft X-ray peak times for 96 flares observed with RHESSI and GOES. These…

Solar and Stellar Astrophysics · Physics 2026-04-07 Brian R. Dennis , Hugh Hudson , Joel Allred

Where and how flares efficiently accelerate charged particles remains an unresolved question. Recent studies revealed that a "magnetic bottle" structure, which forms near the bottom of a large-scale reconnection current sheet above the…

Solar and Stellar Astrophysics · Physics 2024-07-23 Bin Chen , Xiangliang Kong , Sijie Yu , Chengcai Shen , Xiaocan Li , Fan Guo , Yixian Zhang , Lindsay Glesener , Säm Krucker

Recent detection of superflares on solar-type stars by Kepler mission raised a possibility that they can be associated with energetic coronal mass ejections (CMEs) and energetic particle events (SEPs). These space weather events can impact…

Solar and Stellar Astrophysics · Physics 2019-06-26 Shuai Fu , Yong Jiang , Vladimir Airapetian , Junxiang Hu , Gang Li , Gary Zank

Flares are intense explosions on the solar and stellar surfaces, and solar flares are sometimes accompanied by filament or prominence eruptions. Recently, a large filament eruption associated with a superflare on a solar-type star EK Dra…

Solar and Stellar Astrophysics · Physics 2024-01-10 Kai Ikuta , Kazunari Shibata

Solar energetic particles (SEPs) are an important space radiation source, especially for the space weather environment in the inner heliosphere. The energy spectrum of SEP events is crucial both for evaluating their radiation effects and…

Solar and Stellar Astrophysics · Physics 2024-10-18 Yubao Wang , Jingnan Guo