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Context. X-ray flares are common phenomena in pre-main sequence stars. Their analysis gives insights into the physics at work in young stellar coronae. The Orion Nebula Cluster offers a unique opportunity to study large samples of young low…

Astrophysics · Physics 2009-11-13 M. Caramazza , E. Flaccomio , G. Micela , F. Reale , S. J. Wolk , E. D. Feigelson

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

Sympathetic solar flares are eruptions that occur nearby in space and time, driven by an apparent interaction between the active regions in which they are triggered. Their statistical existence on the Sun has yet to be firmly established.…

Solar and Stellar Astrophysics · Physics 2025-02-05 Louis-Simon Guité , Antoine Strugarek , Paul Charbonneau

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

The aim of the present paper is to use quasi-periodic oscillations in hard X-rays (HXRs) of solar flares as a diagnostic tool for investigation of impulsive electron acceleration. We have selected a number of flares which showed…

Solar and Stellar Astrophysics · Physics 2015-05-13 J. Jakimiec , M. Tomczak

Solar flares and X-ray plasma ejections (XPEs) occur simultaneously but usually are separated spatially. We present two exceptional events observed by {\sl Yohkoh} in 2001 October 2 (event 1) and 2000 October 16 (event 2), in which features…

Solar and Stellar Astrophysics · Physics 2013-03-11 Michal Tomczak

Aims. The H-alpha emission of solar flare kernels and associated hard X-ray (HXR) emission often show similar time variations but their light curves are shifted in time by energy transfer mechanisms. We searched for fast radiative response…

Solar and Stellar Astrophysics · Physics 2015-05-30 K. Radziszewski , P. Rudawy , K. J. H. Phillips

We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active…

Solar flares are transient yet dramatic events in the atmosphere of the Sun, during which a vast amount of magnetic energy is liberated. This energy is subsequently transported through the solar atmosphere or into the heliosphere, and…

Solar and Stellar Astrophysics · Physics 2022-12-14 Graham S. Kerr

Most stellar flares' soft X-ray lightcurves possess a `typical' morphology, which consists of a rapid rise followed by a slow exponential decay. However, a study of 216 of the brightest flares on 161 pre-main sequence stars, observed during…

Solar and Stellar Astrophysics · Physics 2015-05-30 C. P. Johnstone , S. G. Gregory , M. M. Jardine , K. V. Getman

In this article, we review some key aspects of a multi-wavelength flare which have essentially contributed to form a standard flare model based on the magnetic reconnection. The emphasis is given on the recent observations taken by the…

Solar and Stellar Astrophysics · Physics 2012-11-14 Bhuwan Joshi , Astrid Veronig , P. K. Manoharan , B. V. Somov

We present the relation of the spatial distribution of H-alpha kernels with the distribution of hard X-ray (HXR) sources seen during the 2001 April 10 solar flare. This flare was observed in H-alpha with the (Sartorius) telescope at Kwasan…

The acceleration and transport of energetic electrons during solar flares is one of the outstanding topics in solar physics. Recent X-ray and radio imaging and spectroscopy observations have provided diagnostics of the distribution of…

Solar and Stellar Astrophysics · Physics 2022-12-21 Xiangliang Kong , Bin Chen , Fan Guo , Chengcai Shen , Xiaocan Li , Jing Ye , Lulu Zhao , Zelong Jiang , Sijie Yu , Yao Chen , Joe Giacalone

We explore the empirical power-law relationship between X-ray luminosity (Lx) and total surface magnetic flux (Phi), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and…

[Abridged]We present analysis of a pair of unusually energetic coronal hard X-ray (HXR) sources detected by RHESSI during the impulsive phase of an X3.9 class solar flare on 2003 November 3, which simultaneously shows two intense footpoint…

Solar and Stellar Astrophysics · Physics 2015-06-03 Qingrong Chen , Vahe Petrosian

Typical solar flares display two quasi-parallel, bright ribbons on the chromosphere. In between is the polarity inversion line (PIL) separating concentrated magnetic fluxes of opposite polarity in active regions (ARs). Intriguingly a series…

Solar and Stellar Astrophysics · Physics 2016-09-30 Rui Liu , Jun Chen , Yuming Wang , Kai Liu

The spectrum of gyrosynchrotron emission from solar flares generally peaks in the microwave range. Its optically-thin, high-frequency component, above the spectral peak, is often used for diagnostics of the nonthermal electrons and the…

Solar and Stellar Astrophysics · Physics 2018-11-07 Gregory D. Fleishman , Maria A. Loukitcheva , Varvara Yu. Kopnina , Gelu M. Nita , Dale E. Gary

The cause of quasi-periodic pulsations (QPP) in solar flares remains the subject of debate. Recently, Nakariakov & Zimovets (2011) proposed a new model suggesting that, in two-ribbon flares, such pulsations could be explained by propagating…

Solar and Stellar Astrophysics · Physics 2013-03-27 A. R. Inglis , B. R. Dennis

During a solar flare, electrons are accelerated to non-thermal energies as a result of magnetic reconnection. These electrons then propagate upwards and downwards from the energy release site along magnetic field lines and produce radio and…

Solar and Stellar Astrophysics · Physics 2025-03-04 Shilpi Bhunia , Laura A. Hayes , Karl Ludwig Klein , Nicole Vilmer , Shane A. Maloney , Peter T. Gallagher

A catalogue of X-ray Plasma Ejections (XPEs) observed by the Soft X-ray Telescope onboard the YOHKOH satellite has been recently developed in the Astronomical Institute of the University of Wroc{\l}aw. The catalogue contains records of 368…

Solar and Stellar Astrophysics · Physics 2015-06-03 Michal Tomczak , Ewa Chmielewska