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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 investigate how the magnetic loop length of solar flares relates to the timing between their thermal and nonthermal emission signatures. Our study analyzes a sample of 96 C-, M-, and X-class flares observed between 2013 and 2015 with…

Solar and Stellar Astrophysics · Physics 2026-02-24 S. M. Perriyil , S. S. Sadangaya , C. G. Giménez de Castro , P. J. A. Simões

We report a NuSTAR observation of a solar microflare, SOL2015-09-01T04. Although it was too faint to be observed by the GOES X-ray Sensor, we estimate the event to be an A0.1 class flare in brightness. This microflare, with only 5 counts…

We analyze high cadence high resolution observations of a C3.2 flare obtained by AIA/SDO on August 1, 2010. The flare is a long duration event with soft X-ray and EUV radiation lasting for over four hours. Analysis suggests that magnetic…

Solar and Stellar Astrophysics · Physics 2015-06-03 Jiong Qiu , Wen-Juan Liu , Dana W. Longcope

We report the first detection of >100 MeV gamma rays associated with a behind-the-limb solar flare, which presents a unique opportunity to probe the underlying physics of high-energy flare emission and particle acceleration. On 2013 October…

Solar and Stellar Astrophysics · Physics 2015-06-03 Melissa Pesce-Rollins , Nicola Omodei , Vahe' Petrosian , Wei Liu , Fatima Rubio da Costa , Alice Allafort , Qingrong Chen

The white-light continuum emissions in solar flares (i.e., white-light flares) are usually observed on the solar disk but, in a few cases, off the limb. Here we present on-disk as well as off-limb continuum emissions at 3600 {\AA} (in the…

Solar and Stellar Astrophysics · Physics 2024-02-13 Ying Li , Zhichen Jing , De-Chao Song , Qiao Li , Jun Tian , Xiaofeng Liu , Ya Wang , M. D. Ding , Andrea Francesco Battaglia , Li Feng , Hui Li , Weiqun Gan

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

Off-limb observations of the solar corona after Coronal Mass Ejections (CMEs) often show strong, compact, and persistent UV sources behind the eruption. They are primarily observed by the SOHO/UVCS instrument in the "hot" Fe XVIII…

Solar and Stellar Astrophysics · Physics 2015-06-17 Roberto Susino , Alessandro Bemporad , Säm Krucker

The interrelation of hard X-ray (HXR) emitting sources and the underlying physics of electron acceleration and transport presents one of the major questions in high-energy solar flare physics. Spatially resolved observations of solar flares…

Solar and Stellar Astrophysics · Physics 2015-06-12 Paulo J. A. Simões , Eduard P. Kontar

Recent measurements of vertical extents and positions of the chromospheric hard X-ray (HXR) flare sources based on Ramaty High-Energy Spectroscopic Imager (RHESSI) observations show a significant inconsistency with the theoretical…

Solar and Stellar Astrophysics · Physics 2016-12-07 Z. Moravec , M. Varady , J. Kasparova , D. Kramolis

The abundance of chlorine is determined from X-ray spectra obtained with the RESIK instrument on {\em CORONAS-F} during solar flares between 2002 and 2003. Using weak lines of He-like Cl, \ion{Cl}{16}, between 4.44 and 4.50 \AA, and with…

Solar and Stellar Astrophysics · Physics 2015-05-28 B. Sylwester , K. J. H. Phillips , J. Sylwester , V. D. Kuznetsov

The disparate nature of thermal-nonthermal energy partition during flares, particularly during weak flares, is still an open issue. Following the Neupert effect, quantifying the relative yield of X-ray emission in different energy bands can…

Solar and Stellar Astrophysics · Physics 2024-02-06 Arun Kumar Awasthi , Tomasz Mrozek , Sylwester Kołomański , Michalina Litwicka , Marek Stęślicki , Karol Kułaga

Context: Weak flares are supposed to be an important heating agent of the outer layers of stellar atmospheres. However, due to instrumental limitations, only large X-ray flares have been studied in detail until now. Aims: We used an…

Astrophysics · Physics 2009-11-13 I. Crespo-Chacón , G. Micela , F. Reale , M. Caramazza , J. López-Santiago , I. Pillitteri

The relationship between X-ray and UV emission during flares, particularly in the context of quasi-periodic pulsations, remains unclear. To address this, we study the impulsive X-ray and UV emission during the eruptive flare of 2011 June 7…

Solar and Stellar Astrophysics · Physics 2015-06-16 Andrew R. Inglis , Holly R. Gilbert

Enhanced continuum brightness is observed in many flares (''white light flares''), yet it is still unclear which processes contribute to the emission. To understand the transport of energy needed to account for this emission, we must first…

Solar and Stellar Astrophysics · Physics 2016-01-27 Lucia Kleint , Petr Heinzel , Phil Judge , Säm Krucker

This Research Note is in response to the recent paper by S. M. Perriyil et al. (2026). They provide measurements of the time delay (delta t) between the hard X-ray and soft X-ray peak times for 96 flares observed with RHESSI and GOES. These…

Solar and Stellar Astrophysics · Physics 2026-04-07 Brian R. Dennis , Hugh Hudson , Joel Allred

We present an analysis of the X-ray properties of a sample of solar- and late-type field stars identified in the Chandra Cosmic Evolution Survey (COSMOS), a deep (160ks) and wide (0.9 deg2) extragalactic survey. The sample of 60 sources was…

Solar and Stellar Astrophysics · Physics 2015-05-20 Nicholas J. Wright , Jeremy J. Drake , Francesca Civano

Polarization measurements of hard X-rays from solar flares can provide a direct handle on the extent to which the accelerated electrons are beamed, which, in turn, has important implications for particle acceleration models. Past efforts to…

Astrophysics · Physics 2009-11-07 M. L. McConnell , J. M. Ryan , D. M. Smith , R. P. Lin , A. G. Emslie

This work is part of a systematic X-ray survey of the Taurus star forming complex with XMM-Newton. We study the time series of all X-ray sources associated with Taurus members, to statistically characterize their X-ray variability, and…

Astrophysics · Physics 2009-11-11 B. Stelzer , E. Flaccomio , K. Briggs , G. Micela , L. Scelsi , M. Audard , I. Pillitteri , M. Guedel

The energy of the thermal flare plasma and the kinetic energy of the non-thermal electrons in 14 hard X-ray peaks from 9 medium-sized solar flares have been determined from RHESSI observations. The emissions have been carefully separated in…

Astrophysics · Physics 2007-05-23 Pascal Saint-Hilaire , Arnold O. Benz
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