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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

It is extremely difficult to simulate the details of coronal heating and also make meaningful predictions of the emitted radiation. Thus, testing realistic models with observations is a major challenge. Observational signatures of coronal…

Solar and Stellar Astrophysics · Physics 2022-11-02 James A. Klimchuk , Kalman J. Knizhnik , Vadim M. Uritsky

The aim of this paper is to investigate the spatial structure of the impulsive phase hard X-ray emission from solar flares. This work is motivated by the YOHKOH and the forthcoming HESSI observations. Summarizing past results, it is shown…

Astrophysics · Physics 2009-10-31 Vahe Petrosian , Timothy Q. Donaghy

The origin of hard X-rays and gamma-rays emitted from the solar atmosphere during occulted solar flares is still debated. The hard X-ray emissions could come from flaring loop tops rising above the limb or Coronal Mass Ejections (CME) shock…

This paper reports on the re-analysis of solar flares in which the hard X-rays (HXRs) come predominantly from the corona rather than from the more usual chromospheric footpoints. All of the 26 previously analyzed event time intervals, over…

Solar and Stellar Astrophysics · Physics 2018-11-07 Brian R. Dennis , Miguel A. Duval-Poo , Michele Piana , Andrew R. Inglis , A. Gordon Emslie , Jingnan Guo , Yan Xu

We conducted a high-resolution numerical simulation of the solar corona above a stable active region. The aim is to test the field-line braiding mechanism for a sufficient coronal energy input. We also check the applicability of scaling…

Solar and Stellar Astrophysics · Physics 2018-05-17 Philippe-A. Bourdin , Sven Bingert , Hardi Peter

Two solar type II radio bursts, separated by ~24 hours in time, are examined together. Both events are associated with coronal mass ejections (CMEs) erupting from the same active region (NOAA 11176) beneath a well-observed helmet streamer.…

Solar and Stellar Astrophysics · Physics 2015-06-23 Xiangliang Kong , Yao Chen , Fan Guo , Shiwei Feng , Bing Wang , Guohui Du , Gang Li

We study a coronal mass ejection (CME) associated with an X-class flare, whose initiation is clearly observed in low corona with high-cadence, high-resolution EUV images, providing us a rare opportunity to witness the early evolution of an…

Solar and Stellar Astrophysics · Physics 2014-11-26 Rui Liu , Yuming Wang , Chenglong Shen

Understanding coronal structure and dynamics can be facilitated by analyzing green-line emission, which enables the investigation of diverse coronal structures such as coronal loops, streamers, coronal holes, and various eruptions in the…

Solar and Stellar Astrophysics · Physics 2024-11-27 Jacob Oloketuyi , Yu Liu , Linhua Deng , Abouazza Elmhamdi , Fengrong Zhu , Ayodeji Ibitoye , Opeyemi Omole , Feiyang Sha , Qiang Liu

Current models of gamma-ray lightcurves in pulsars suffer from large uncertainties on the precise location of particle acceleration and radiation. Here, we present an attempt to alleviate these difficulties by solving for the…

High Energy Astrophysical Phenomena · Physics 2016-02-17 Benoît Cerutti , Alexander A. Philippov , Anatoly Spitkovsky

In present paper, we describe a theoretical model of generation of harmonic emissions of type III solar radio bursts. The goal of our study is to fully take into account the most efficient physical processes participating in generation of…

Plasma Physics · Physics 2021-02-24 Anna Tkachenko , Vladimir Krasnoselskikh , Andrii Voshchepynets

Context. Coronal mass ejections (CMEs) are large eruptions of magnetised plasma from the Sun that are often accompanied by solar radio bursts produced by accelerated electrons. Aims. A powerful source for accelerating electron beams are…

Solar and Stellar Astrophysics · Physics 2020-10-14 D. E. Morosan , E. Palmerio , J. E. Räsänen , E. K. J. Kilpua , J. Magdalenić , B. J. Lynch , A. Kumari , J. Pomoell , M. Palmroth

Coronal loops in active regions are the subjects of intensive investigation, but the important diffuse 'unresolved' emission in which they are embedded has received relatively little attention. Here we measure the densities and emission…

Solar and Stellar Astrophysics · Physics 2019-03-06 David H. Brooks

Energy spectra and angular distributions have been measured of electrons that are emitted upon disassembly of $Xe_{150000}$ following irradiation by intense (10$^{15}-10^{16}$ W cm$^{-2}$) laser pulses whose durations are varied over the…

Atomic and Molecular Clusters · Physics 2009-11-07 V. Kumarappan , M. Krishnamurthy , D. Mathur

This paper presents the latest observations from the newly-built solar radio spectrograph at the \emph{Chashan Solar Observatory}. On July 18 2016, the spectrograph records a solar spike burst event, which has several episodes showing…

Solar and Stellar Astrophysics · Physics 2018-02-14 Shiwei Feng , Yao Chen , Chuanyang Li , Bing Wang , Zhao Wu , Xiangliang Kong , Qingfu Du , Junrui Zhang , Guoqing Zhao

Since the early 1980s, decimetric spike bursts have been attributed to electron cyclotron maser emission (ECME) by the electrons that produce hard X-ray bursts as they precipitate into the chromosphere in the impulsive phase of a solar…

Solar and Stellar Astrophysics · Physics 2016-11-15 D. B. Melrose , M. S. Wheatland

Long-period radio transients (LPRTs) are highly polarised, coherent radio sources with periods of minutes to hours and bursts typically lasting 10 to 100 s. Here we consider the apparently isolated subclass of LPRTs and argue that electron…

High Energy Astrophysical Phenomena · Physics 2026-02-18 Lilia Ferrario

This Brief Communication presents a quantitative investigation for the effect of electron holes on electron-cyclotron maser (ECM) driven by horseshoe distributions. The investigation is based on an integrated distribution function for the…

Plasma Physics · Physics 2016-12-21 G. Q. Zhao , Y. H. Chu , H. Q. Feng , D. J. Wu

Solar type II radio bursts are commonly attributed to coronal shocks driven by coronal mass ejections (CMEs). However, some metric type II bursts have occasionally been reported to occur in the absence of a CME and to be associated with…

Solar and Stellar Astrophysics · Physics 2025-12-23 Yingli Cui , Xiangliang Kong , Zhentong Li , Bing Wang , Yadan Duan , Ze Zhong , Hao Ning , Zhao Wu , Manqing Wang , Yang Liu , Feiyu Yu , Zelong Jiang , Wei Chen , Yang Su , Yao Chen

Coronal mass ejections (CMEs) on stars other than the Sun have proven very difficult to detect. One promising pathway lies in the detection of type II radio bursts. Their appearance and distinctive properties are associated with the…