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Finite thermal velocity modifications to electron slowing-down rates may be important for the deduction of solar flare total electron energy. Here we treat both slowing-down and velocity diffusion of electrons in the corona at flare…

Astrophysics · Physics 2009-11-11 Ross K. Galloway , Alexander L. MacKinnon , Eduard P. Kontar , Per Helander

This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form…

Imaging spectroscopy in X-rays with RHESSI provide the possibility to investigate the spatial evolution of the X-ray emitting electron distribution and therefore to study the transport effects on energetic electrons during solar flares. We…

Solar and Stellar Astrophysics · Physics 2018-02-07 S. Musset , E. P. Kontar , N. Vilmer

Non-potential magnetic energy promptly released in solar flares is converted to other forms of energy. This may include nonthermal energy of flare-accelerated particles, thermal energy of heated flaring plasma, and kinetic energy of…

Solar and Stellar Astrophysics · Physics 2021-06-09 Gregory D. Fleishman , Lucia Kleint , Galina G. Motorina , Gelu M. Nita , Eduard P. Kontar

Solar flare precursors depict constrained rate of energy release contrasting the imminent rapid energy release which calls for different regime of plasma processes to be at play. Due to subtle emission during the precursor phase, its…

Solar and Stellar Astrophysics · Physics 2018-05-23 Arun Kumar Awasthi , Pawel Rudawy , Robert Falewicz , Arkadiusz Berlicki , Rui Liu

We highlight ten key aspects of coronal heating that must be understood before we can consider the problem to be solved. (1) All coronal heating is impulsive. (2) The details of coronal heating matter. (3) The corona is filled with…

Solar and Stellar Astrophysics · Physics 2015-04-13 James A. Klimchuk

Solar flares effectively accelerate particles to non-thermal energies. These accelerated electrons are responsible for energy transport and subsequent emissions in HXR, radio, and UV/EUV radiation. Due to the steeply decreasing electron…

Solar and Stellar Astrophysics · Physics 2026-01-01 Yingjie Luo , Eduard P. Kontar , Debesh Bhattacharjee

Solar flare ribbon fronts appear ahead of the bright structures that normally characterise solar flares, and can persist for an extended period of time in spatially localised patches before transitioning to `regular' bright ribbons. They…

Solar and Stellar Astrophysics · Physics 2024-05-07 Graham S. Kerr , Vanessa Polito , Yan Xu , Joel C. Allred

\textbf{Purpose:} This paper addresses long-standing solar physics problems, namely, the heating of the solar chromosphere and the origin of the solar wind. Our aim is to reveal the related mechanisms behind chromospheric heating and plasma…

Solar and Stellar Astrophysics · Physics 2022-12-07 K. Murawski , Z. E. Musielak , S. Poedts , A. K. Srivastava , L. H. S. Kadowaki

Using a non-linear Monte-Carlo code we investigate the radiative response of an accretion disk corona system to static homogeneous flares. We model a flare by a rapid (comparable to the light crossing time) energy dissipation in the corona…

Astrophysics · Physics 2016-08-30 Julien Malzac , Elisabeth Jourdain

The solar flare on July 30, 2011 was of a modest X-ray class (M9.3), but it made a strong photospheric impact and produced a "sunquake," observed with the Helioseismic and Magnetic Imager (HMI) on NASA's Solar Dynamics Observatory (SDO). In…

Solar and Stellar Astrophysics · Physics 2015-08-06 I. N. Sharykin , A. G. Kosovichev

It is extremely difficult to simulate the details of coronal heating and also make meaningful predictions of the emitted radiation. Thus, testing realistic models with observations is a major challenge. Observational signatures of coronal…

Solar and Stellar Astrophysics · Physics 2022-11-02 James A. Klimchuk , Kalman J. Knizhnik , Vadim M. Uritsky

Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal…

Solar and Stellar Astrophysics · Physics 2018-03-14 Lucie Green , Tibor Torok , Bojan Vrsnak , Ward Manchester , Astrid Veronig

For many years various asymmetrical profiles of different spectral lines emitted from solar flares have been frequently observed. These asymmetries or line shifts are caused predominantly by vertical mass motions in flaring layers and they…

Astrophysics · Physics 2007-05-23 A. Berlicki

Solar flares form and release energy across a large number of magnetic loops. The global parameters of flares, such as the total energy released, duration, physical size, etc., are routinely measured, and the hydrodynamics of a coronal loop…

Solar and Stellar Astrophysics · Physics 2018-04-18 Jeffrey W. Reep , Vanessa Polito , Harry P. Warren , Nicholas A. Crump

An integrated Magneto-Fluid model, that accords full treatment to the Velocity fields associated with the directed plasma motion, is developed to investigate the dynamics of coronal structures. It is suggested that the interaction of the…

Since the advent of X-ray and EUV spectroscopy, the discovery of the First Ionization Potential (FIP) effect--where coronal elemental compositions diverge from their photospheric values based on the element's FIP--has remained a key puzzle…

Solar and Stellar Astrophysics · Physics 2025-10-03 Biswajit Mondal , Amy R. Winebarger

The energy released in a solar flare is partitioned between thermal and non-thermal particle energy and lost to thermal conduction and radiation over a broad range of wavelengths. It is difficult to determine the conductive losses and the…

Astrophysics · Physics 2011-02-11 J. C. Raymond , G. Holman , A. Ciaravella , A. Panasyuk , Y. -K. Ko , J. Kohl

Spatially-resolved X-ray observations are the key to understanding electron acceleration in solar flares. Currently, the underlying processes that efficiently energize solar flare particles are poorly constrained. Abundant flare…

Solar and Stellar Astrophysics · Physics 2026-03-09 Morgan Stores , Natasha Jeffrey , Ewan Dickson , James McLaughlin , Eduard Kontar

The solar corona is a template to understand stellar activity. The Sun is a moderately active star, and its corona differs from active stars: active stellar coronae have a double-peaked EM(T) with the hot peak at 8-20 MK, while the non…

Astrophysics · Physics 2009-11-13 C. Argiroffi , G. Peres , S. Orlando , F. Reale