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The 'standard solar' flare model collects all physical ingredients identified by multi-wavelength observations of our Sun: magnetic reconnection, fast particle acceleration and the resulting emission at various wavelengths, especially in…

Solar and Stellar Astrophysics · Physics 2020-06-24 Wenzhi Ruan , Chun Xia , Rony Keppens

Recent observations in extreme-ultraviolet (EUV) wavelengths reveal a new late phase in some solar flares, which is seen as a second peak in warm coronal emissions ($\sim3$ MK) several tens of minutes to a few hours after the soft X-ray…

Solar and Stellar Astrophysics · Physics 2021-08-04 Y. Zhong , Y. Dai , M. D. Ding

The bulk of solar flare emission originates from very compact sources located in the lower solar atmosphere and seen in various wavelength ranges: near optical, UV, EUV, soft and hard X-rays, and gamma-ray emission, yet very few spatially…

Solar and Stellar Astrophysics · Physics 2015-05-28 Marina Battaglia , Eduard P. Kontar

Two kinds of processes could occur during the flare decay phase: processes of energy release or processes of energy relaxation. Quasi-periodic pulsations (QPPs) of the broadband emission are a good tool for the verification of mechanisms.…

We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability…

Solar and Stellar Astrophysics · Physics 2021-05-05 Dong Li , Alexander Warmuth , Lei Lu , Zongjun Ning

In this paper, the energy budgets of two single-loop like flares observed in X- ray are analysed under the assumption that non-thermal electrons (NTEs) are the only source of plasma heating during all phases of both events. The flares were…

Solar and Stellar Astrophysics · Physics 2014-06-19 R. Falewicz

Recent observations in extreme-ultraviolet (EUV) wavelengths reveal an EUV late phase in some solar flares that is characterized by a second peak in warm coronal emissions ($\sim3$~MK) several tens of minutes to a few hours after the soft…

Solar and Stellar Astrophysics · Physics 2018-05-02 Yu Dai , Mingde Ding

Flare emissions in X-ray and EUV wavelengths have previously been modeled as the plasma response to impulsive heating from magnetic reconnection. Some flares exhibit gradually evolving X-ray and EUV light curves, which are believed to…

Solar and Stellar Astrophysics · Physics 2016-04-20 Jiong Qiu , Dana W. Longcope

Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional…

Solar and Stellar Astrophysics · Physics 2014-04-04 Wei Liu , Qingrong Chen , Vahe' Petrosian

One of the key processes associated with the "standard" flare model is chromospheric evaporation, a process where plasma heated to high temperatures by energy deposition at the flare footpoints is driven upwards into the corona. Despite…

We present analysis of the magnetic field in seven solar flare regions accompanied by the pulsations of hard X-ray (HXR) emission. These flares were studied by Kuznetsov et al. (2016) (Paper~I), and chosen here because of the availability…

Solar and Stellar Astrophysics · Physics 2018-05-16 I. V. Zimovets , R. Wang , Y. D. Liu , C. C. Wang , S. A. Kuznetsov , I. N. Sharykin , A. B. Struminsky , V. M. Nakariakov

X-ray observations are a direct diagnostic of fast electrons produced in solar flares, energized during the energy release process and directed towards the Sun. Since the properties of accelerated electrons can be substantially changed…

Solar and Stellar Astrophysics · Physics 2015-10-28 Natasha Jeffrey , Eduard Kontar , Gordon Emslie , Nicolas Bian

Spectroscopic observations in X-ray wavelengths provide excellent diagnostics of the temperature distribution in solar flare plasma. The Solar X-ray Monitor (XSM) onboard the Chandrayaan-2 mission provides broad-band disk integrated soft…

We present the analyses of intense X-ray flares detected on the active fast rotator AB Dor using observations from the XMM-Newton. A total of 21 flares are detected, and 13 flares are analysed in detail. The total X-ray energy of these…

Solar and Stellar Astrophysics · Physics 2023-10-23 Shweta Didel , Jeewan C. Pandey , A. K. Srivastava , Gurpreet Singh

An X-ray flaring source was found near the galaxy NGC 4697. Two flares were seen, separated by four years. The flux increased by a factor of 90 on a timescale of about one minute. Both flares were very brief. There is no optical counterpart…

Svestka (Solar Phys. 1989, 121, 399) on the basis of the Solar Maximum Mission observations introduced a new class of flares, the so-called flare hybrids. When they start, they look as typical compact flares (phase 1), but later on they…

Solar and Stellar Astrophysics · Physics 2015-05-20 M. Tomczak , P. Dubieniecki

We present the results of a search of the XMM-Newton public data archive for stellar X-ray flares. We find eight flaring sources for which we identify 7 optical counterparts. Three of these sources have distance estimates which allow us to…

Astrophysics · Physics 2009-11-10 Duncan Trenholme , Gavin Ramsay , Carl Foley

Double coronal hard X-ray (HXR) sources are believed to be critical observational evidence of bi-directional energy release through magnetic reconnection in a large-scale current sheet in solar ares. Here we present a study on double…

Solar and Stellar Astrophysics · Physics 2017-07-05 Yao Chen , Zhao Wu , Wei Liu , Richard A. Schwartz , Di Zhao , Bing Wang , Guohui Du

We investigate accelerated electron energy spectra for different sources in a large flare using simultaneous observations obtained with two instruments, the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz, and the Reuven Ramaty High…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. R. Kundu , V. V. Grechnev , S. M. White , E. J. Schmahl , N. S. Meshalkina , L. K. Kashapova

A multi-wavelength spatial and temporal analysis of solar high energy electrons is conducted using the August 20, 2002 flare of an unusually flat (gamma=1.8) hard X-ray spectrum. The flare is studied using RHESSI, Halpha, radio, TRACE, and…

Astrophysics · Physics 2008-11-26 J. Kasparova , M. Karlicky , E. P. Kontar , R. A. Schwartz , B. R. Dennis