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The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. The chromosphere and transition region (TR) form an interface region between the surface and the corona that…

M-dwarf flares observed by the \textit{Transiting Exoplanet Survey Satellite} (\textit{TESS}) sometimes exhibit a "peak-bump" light-curve morphology, characterized by a secondary, gradual peak well after the main, impulsive peak. A similar…

Solar and Stellar Astrophysics · Physics 2023-10-31 Kai E. Yang , Xudong Sun , Graham S. Kerr , Hugh S. Hudson

The soft X-ray emissions of solar flares come mainly from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy,…

Solar and Stellar Astrophysics · Physics 2015-06-03 Paulo J. A. Simões , Hugh S. Hudson , Lyndsay Fletcher

In our recent paper (Solar Physics 261, 233) we investigated quasi-periodic oscillations of hard X-rays during impulsive phase of solar flares. We have come to conclusion that they are caused by magnetosonic oscillations of magnetic traps…

Solar and Stellar Astrophysics · Physics 2015-06-17 J. Jakimiec , M. Tomczak

We explore the temporal relationship between microwave/HXR emission and Doppler velocity during the impulsive phase of a solar flare on 2014 October 27 (SOL2014-10-27), which displays a pulse on the light curves in microwave (34 GHz) and…

Solar and Stellar Astrophysics · Physics 2017-05-24 Dong Li , Zongjun Ning , Yu Huang , Qingmin Zhang

We present direct evidence for the detection of the main energy release site in a non-eruptive solar flare, SOL2013-11-09T06:38UT. This GOES C2.7 event was characterised by two flaring ribbons and a compact, bright coronal source located…

Solar and Stellar Astrophysics · Physics 2015-05-06 Paulo J. A. Simões , David R. Graham , Lyndsay Fletcher

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

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 flares result from the rapid conversion of stored magnetic energy within the Sun's corona. These energy releases are associated with coronal magnetic loops, which are rooted in dense photospheric plasma and are passively transported…

Solar and Stellar Astrophysics · Physics 2025-03-28 M. Berretti , S. Mestici , L. Giovannelli , D. Del Moro , M. Stangalini , F. Giannattasio , F. Berrilli

Microflares have been considered to be among the major energy input sources to form active solar corona. To investigate the response of the low atmosphere to events, we conducted an ALMA observation at 3 mm coordinated with IRIS and Hinode…

Solar and Stellar Astrophysics · Physics 2021-12-08 Toshifumi Shimizu , Masumi Shimojo , Masashi Abe

Solar flares are widely accepted to be powered by magnetic reconnection that involves complex dynamics in various scales. The flare supra-arcade and loop-top region, directly impacted by fast reconnection downflows, contains a wealth of…

Solar and Stellar Astrophysics · Physics 2025-05-27 Tingyu Gou , Katharine K. Reeves

X-ray and EUV observations are an important diagnostic of various plasma parameters of the solar atmosphere during solar flares. Soft X-ray and EUV observations often show coronal sources near the top of flaring loops, while hard X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-11 Marina Battaglia , Eduard P. Kontar

Properties of the solar radio spectrum, as well as the temporal profiles of flare emission, indicate the thermal nature of the sub-terahertz (sub-THz) component observed as the growth of radio emission in the frequency range of 100-1000…

Solar and Stellar Astrophysics · Physics 2023-11-07 G. G. Motorina , Yu. T. Tsap , V. V. Smirnova , A. S. Morgachev , A. D. Shramko , A. S. Motorin

The recent discovery of impulsive solar burst emission in the 30 THz band is raising new interpretation challenges. One event associated with a GOES M2 class flare has been observed simultaneously in microwaves, H-alpha, EUV, and soft X-ray…

Before the onset of a flare is observed in hard X-rays there is often a prolonged pre-flare or pre-heating phase with no detectable hard X-ray emission but pronounced soft X-ray emission suggesting that energy is being released and…

Solar and Stellar Astrophysics · Physics 2015-06-19 Marina Battaglia , Lyndsay Fletcher , Paulo J. A. Simões

The energy released during solar flares is believed to be stored in non-potential magnetic fields associated with electric currents flowing in the corona. While no measurements of coronal electric currents are presently available, maps of…

Solar and Stellar Astrophysics · Physics 2015-08-19 Sophie Musset , Nicole Vilmer , Véronique Bommier

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…

The time evolution of the spectral index and the non-thermal flux in 24 impulsive solar hard X-ray flares of GOES class M was studied in RHESSI observations. The high spectral resolution allows for a clean separation of thermal and…

Astrophysics · Physics 2007-05-23 Paolo C. Grigis , Arnold O. Benz

We performed statistical and event studies of linear polarization in the H$\alpha$ line during solar flares. The statistical study revealed that, among 71 H$\alpha$ flares analyzed, including 64 GOES flares, only one event shows significant…

Solar and Stellar Astrophysics · Physics 2019-02-20 Tomoko Kawate , Yoichiro Hanaoka

We carried out detailed analysis of X-ray and radio observations of a simple flare loop that occurred on 12th August 2002, with the impulsive hard X-ray (HXR) light curves dominated by a single pulse. The emission spectra of the early…

Solar and Stellar Astrophysics · Physics 2015-06-22 I. N. Sharykin , S. Liu , L. Fletcher