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The hard X-ray (HXR) emission in solar flares comes almost exclusively from a very small part of the flaring region, the footpoints of magnetic loops. Using RHESSI observations of solar flare footpoints, we determine the radial positions…

Solar and Stellar Astrophysics · Physics 2015-05-27 Marina Battaglia , Eduard P. Kontar

Decades of astrophysical observations have convincingly shown that soft X-ray (SXR; ~0.1--10 keV) emission provides unique diagnostics for the high temperature plasmas observed in solar flares and active regions. SXR observations critical…

Instrumentation and Methods for Astrophysics · Physics 2017-01-04 Amir Caspi , Albert Y. Shih , Harry P. Warren , Marek Stęślicki , Janusz Sylwester

The sites of chromospheric excitation during solar flares are marked by extended extreme ultraviolet ribbons and hard X-ray footpoints. The standard interpretation is that these are the result of heating and bremsstrahlung emission from…

Solar and Stellar Astrophysics · Physics 2014-01-28 L. Fletcher , I. G. Hannah , H. S. Hudson , D. E. Innes

A popular scenario for electron acceleration in solar flares is transit-time damping of low-frequency MHD waves excited by reconnection and its outflows. The scenario requires several processes in sequence to yield energetic electrons of…

Astrophysics · Physics 2015-06-24 Arnold O. Benz , Pascal Saint-Hilaire

The optical and near-ultraviolet (NUV) continuum radiation in M dwarf flares is thought to be the impulsive response of the lower stellar atmosphere to magnetic energy release and electron acceleration at coronal altitudes. This radiation…

Solar and Stellar Astrophysics · Physics 2023-02-07 Adam F. Kowalski

NuSTAR is a highly sensitive focusing hard X-ray (HXR) telescope and has observed several small microflares in its initial solar pointings. In this paper, we present the first joint observation of a microflare with NuSTAR and Hinode/XRT on…

We present a detailed multi-wavelength study of the M6.2 flare which was associated with a confined eruption of a prominence using TRACE, RHESSI, and NoRH observations. The pre-flare phase of this event is characterized by spectacular…

Solar and Stellar Astrophysics · Physics 2015-07-15 Upendra Kushwaha , Bhuwan Joshi , Astrid M. Veronig , Yong-Jae Moon

We present the statistical analysis of 33 flare-related coronal jets, and discuss the link between the jet and the flare properties in these events. We selected jets that were observed between 2010 and 2016 by the Atmospheric Imaging…

Solar and Stellar Astrophysics · Physics 2020-02-12 Sophie Musset , Mariana Jeunon , Lindsay Glesener

Analysis of the observations of the SOL2001-12-26 event related to ground-level-event GLE63, including microwave spectra and images from NoRH at 17 and 34 GHz, SSRT at 5.7 GHz, and TRACE in 1600 \AA\ has led to the following results. A…

Solar and Stellar Astrophysics · Physics 2016-12-14 V. V. Grechnev , A. M. Uralov , V. I. Kiselev , A. A. Kochanov

Investigate the spatial and spectral evolution of hard X-ray (HXR) emission from flare accelerated electron beams subject to collisional transport and wave-particle interactions in the solar atmosphere. We numerically follow the propagation…

Solar and Stellar Astrophysics · Physics 2015-05-27 I. G. Hannah , E. P. Kontar

We analytically and numerically study the motion of electrons along a magnetic loop, to compare with the observation of the propagating feature of the non-thermal microwave source in the 1999 August 28 solar flare reported by Yokoyama et…

Astrophysics · Physics 2009-11-13 T. Minoshima , T. Yokoyama

Filament eruptions and hard X-ray (HXR) source motions are commonly observed in solar flares, which provides critical information on the coronal magnetic reconnection. This Letter reports an event on 2005 January 15, in which we found an…

Solar and Stellar Astrophysics · Physics 2015-05-19 Chang Liu , Jeongwoo Lee , Ju Jing , Rui Liu , Na Deng , Haimin Wang

This paper continues the cycle of authors' works on the detection of precursors of large flares (M5 and higher classes) in active regions (ARs) of the Sun by their microwave radiation and magnetographic characteristics. Generalization of…

Solar and Stellar Astrophysics · Physics 2017-11-28 V. E. Abramov-Maximov , V. N. Borovik , L. V. Opeikina , A. G. Tlatov , L. V. Yasnov

We study a solar flare that occurred on September 10, 2002, in active region NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the radio range. The event was classified as M2.9 in X-rays and 1N in H\alpha. Solar…

Solar and Stellar Astrophysics · Physics 2015-06-11 C. G. Giménez de Castro , G. D. Cristiani , P. J. A. Simões , C. H. Mandrini , E. Correia , P. Kaufmann

One of the main science questions of the Solar Orbiter and Parker Solar Probe missions deals with understanding how electrons in the lower solar corona are accelerated and how they subsequently access interplanetary space. We aim to…

(Abridged) We report results from a comprehensive study of the nearby M dwarf Proxima Centauri with the XMM-Newton satellite. We find strongly variable coronal X-ray emission, with flares ranging over a factor of 100 in peak flux. The…

Astrophysics · Physics 2009-11-10 M. Guedel , M. Audard , F. Reale , S. L. Skinner , J. L. Linsky

A high-speed halo-type coronal mass ejection (CME), associated with a GOES M4.6 soft X-ray flare in NOAA AR 0180 at S12W29 and an EIT wave and dimming, occurred on 9 November 2002. A complex radio event was observed during the same period.…

Much evidence suggests that the solar corona is heated impulsively, meaning that nanoflares may be ubiquitous in quiet and active regions (ARs). Hard X-ray (HXR) observations with unprecedented sensitivity $>$3~keV are now enabled by…

We report on radiative hydrodynamic simulations of moderate and strong solar flares. The flares were simulated by calculating the atmospheric response to a beam of non-thermal electrons injected at the apex of a one-dimensional closed…

Astrophysics · Physics 2009-11-13 J. C. Allred , S. L. Hawley , W. P. Abbett , M. Carlsson

An X3.4 solar flare and a fast halo coronal mass ejection (CME) occurred on 2006 December 13, accompanied by a high flux of energetic particles recorded both in near-Earth space and at ground level. Our purpose is to provide evidence of…

Solar and Stellar Astrophysics · Physics 2013-05-27 C. Li , Y. Dai , J. -C. Vial , C. J. Owen , S. A. Matthews , Y. H. Tang , C. Fang , A. N. Fazakerley