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The impulsive phase of a solar flare marks the epoch of rapid conversion of energy stored in the pre-flare coronal magnetic field. Hard X-ray observations imply that a substantial fraction of flare energy released during the impulsive phase…

Astrophysics · Physics 2009-11-13 L. Fletcher , H. S. Hudson

Determining the preferred spatial location of the energy input to solar coronal loops would be an important step forward towards a more complete understanding of the coronal heating problem. Following on from Sarkar & Walsh (2008) this…

Solar and Stellar Astrophysics · Physics 2009-07-22 Aveek Sarkar , Robert W Walsh

We have calculated the H$\alpha$ and Ca {\sc ii} 8542 {\AA} line profiles based on four different atmospheric models, including the effects of nonthermal electron beams with various energy fluxes. These two lines have different responses to…

Astrophysics · Physics 2008-11-26 J. X. Cheng , M. D. Ding , J. P. Li

Aims: This work aims to identify the mechanism driving pulsations in hard X-ray (HXR) and microwave emission during solar flares. Here, by using combined HXR and microwave observations from Solar Orbiter/STIX and EOVSA we investigate an…

Solar and Stellar Astrophysics · Physics 2024-05-01 Hannah Collier , Laura A. Hayes , Sijie Yu , Andrea F. Battaglia , William Ashfield , Vanessa Polito , Louise K. Harra , Säm Krucker

Recent irradiance measurements from numerous heliophysics and astrophysics missions including SDO, GOES, Kepler, TESS, Chandra, XMM-Newton, and NICER have provided critical input in understanding the physics of the most powerful transient…

Solar and Stellar Astrophysics · Physics 2023-09-11 Jeffrey W. Reep , Vladimir S. Airapetian

Large solar flares (GOES M-class or higher) are usually associated with eruptions of material. However, when considering flare irradiance enhancements and dynamics such as chromospheric evaporation, potential contributions from erupted…

Solar and Stellar Astrophysics · Physics 2025-12-18 Luke Majury , Marie Dominique , Ryan Milligan , Dana-Camelia Talpeanu , Ingolf Dammasch , David Berghmans

Solar flares involve the sudden release of magnetic energy in the solar corona. Accelerated nonthermal electrons have often been invoked as the primary means for transporting the bulk of the released energy to the lower solar atmosphere.…

Solar and Stellar Astrophysics · Physics 2019-02-20 Sijie Yu , Bin Chen

We present an analysis of soft X-ray (SXR) and extreme-ultraviolet (EUV) observations of solar flares with an approximate C8 GOES class. Our constraint on peak GOES SXR flux allows for the investigation of correlations between various flare…

Solar and Stellar Astrophysics · Physics 2013-05-09 Trevor A. Bowen , Paola Testa , Katharine K. Reeves

We present a multiwavelength study of the X-class flare, which occurred in active region (AR) NOAA 11339 on 3 November 2011. The EUV images recorded by SDO/AIA show the activation of a remote filament (located north of the AR) with…

Solar and Stellar Astrophysics · Physics 2015-06-16 Pankaj Kumar , K. S. Cho

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

A solar flare releases magnetic energy by reconnecting field lines across a current sheet, thereby allowing their relaxation to a lower energy state. The maximum possible energy is released if all field lines relax to a current-free…

Solar and Stellar Astrophysics · Physics 2025-11-03 Drake Osaben , Jiong Qiu , Dana W. Longcope

Context. Extreme ultraviolet (EUV) late-phase (ELP) flares exhibit a second peak in warm coronal emissions minutes to hours after the main peak of the flare. This phase is all but negligible, and it is still poorly understood what role it…

Solar and Stellar Astrophysics · Physics 2025-12-02 Sascha Ornig , Astrid M. Veronig , Karin Dissauer

Since the launch of NASA's Solar Dynamics Observatory on 2010 February 11, the Extreme ultraviolet Variability Experiment (EVE) has observed numerous flares. One interesting feature observed by EVE is that a subset of flares exhibit an…

Solar and Stellar Astrophysics · Physics 2012-02-23 R. A. Hock , T. N. Woods , J. A. Klimchuk , F. G. Eparvier , A. R. Jones

We statistically study the relationship between the Lyman-alpha (\lya) and 1--8 \AA\ soft X-ray (SXR) emissions from 658 M- and X-class solar flares observed by the {\em Geostationary Operational Environmental Satellite} during 2006--2016.…

Solar and Stellar Astrophysics · Physics 2020-11-25 Zhichen Jing , Wuqi Pan , Yukun Yang , Dechao Song , Jun Tian , Y. Li , X. Cheng , Jie Hong , M. D. Ding

We have studied the relationship between the location of EUV nonthermal broadening and high-energy particles during the large flares by using EUV imaging spectrometer onboard {\it Hinode}, Nobeyama Radio Polarimeter, Nobeyama…

Solar and Stellar Astrophysics · Physics 2015-06-16 Tomoko Kawate , Shinsuke Imada

In the present work we study the C8 flare occurred on September 26, 2000 at 19:49 UT and observed by the SOHO/SUMER spectrometer from the beginning of the impulsive phase to well beyond the disappearance in the X-rays. The emission first…

Solar and Stellar Astrophysics · Physics 2015-06-03 F. Reale , E. Landi , S. Orlando

The physical modeling of active regions (ARs) and of the global coronal is receiving increasing interest lately. Recent attempts to model ARs using static equilibrium models were quite successful in reproducing AR images of hot soft X-ray…

Astrophysics · Physics 2009-11-13 S. Patsourakos , J. A. Klimchuk

Solar flares often happen after a preflare / preheating phase, which is almost or entirely thermal. In contrast, there are the so-called early impulsive flares that do not show a (significant) preflare heating but instead often show the…

Solar and Stellar Astrophysics · Physics 2018-04-04 Alexandra L. Lysenko , Alexander T. Altyntsev , Natalia S. Meshalkina , Dmitriy Zhdanov , Gregory D. Fleishman

We present observations of a confined M4.0 flare from NOAA 11302 on 2011 September 26. Observations at high temporal, spatial, and spectral resolution from Solar Dynamics Observatory, Reuven Ramaty High Energy Solar Spectroscopic Imager,…

Solar and Stellar Astrophysics · Physics 2014-08-05 Upendra Kushwaha , Bhuwan Joshi , Kyung-Suk Cho , Astrid Veronig , Sanjiv Kumar Tiwari , S. K. Mathew

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
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