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Related papers: The spectral evolution of impulsive solar X-ray fl…

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We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and in microwaves. We analyzed 12 flares observed by the Hard X-ray Telescope aboard {\it Yohkoh}, Nobeyama Radio Polarimeters (NoRP), and the Nobeyama…

Extending previous studies of nonthermal electron transport in solar flares which include the effects of collisional energy diffusion and thermalization of fast electrons, we present an analytic method to infer more accurate estimates of…

Solar and Stellar Astrophysics · Physics 2015-08-19 E. P. Kontar , N. L. S. Jeffrey , A. G. Emslie , N. H. Bian

The recent discovery of impulsive solar burst emission in the 30 THz band is raising new interpretation challenges. One event associated with a GOES M2 class flare has been observed simultaneously in microwaves, H-alpha, EUV, and soft X-ray…

Hard x-ray spectral breaks are explained in terms of a 1D model with a co-spatial return current. We study 19 flares observed by RHESSI (Ramaty High Energy Solar Spectroscopic Imager) with strong spectral breaks at energies around a few…

Solar and Stellar Astrophysics · Physics 2018-01-08 Meriem Alaoui , Gordon Holman

RHESSI measurements relevant to the fundamental processes of energy release and particle acceleration in flares are summarized. RHESSI's precise measurements of hard X-ray continuum spectra enable model-independent deconvolution to obtain…

Solar and Stellar Astrophysics · Physics 2011-10-11 R. P. Lin

Observational evidence for gentle chromospheric evaporation during the impulsive phase of a C9.1 solar flare is presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the Coronal Diagnostic Spectrometer on…

We propose a nonlinear self-consistent model of the turbulent non-resonant particle acceleration in solar flares. We simulate temporal evolution of the spectra of charged particles accelerated by strong long-wavelength MHD turbulence taking…

Solar and Stellar Astrophysics · Physics 2009-11-13 A. M. Bykov , G. D. Fleishman

Solar flares are efficient particle accelerators with a large fraction of released magnetic energy (10-50%) converted into energetic particles such as hard X-ray producing electrons. This energy transfer process is not well constrained,…

Solar and Stellar Astrophysics · Physics 2023-04-12 Morgan Stores , Natasha L. S. Jeffrey , James A. McLaughlin

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

We present an updated catalog of 113 X-ray flares detected by Swift in the ~33% of the X-ray afterglows of Gamma-Ray Bursts (GRB). 43 flares have a measured redshift. For the first time the analysis is performed in 4 different X-ray energy…

High Energy Astrophysical Phenomena · Physics 2015-05-18 G. Chincarini , J. Mao , R. Margutti , M. G. Bernardini , C. Guidorzi , F. Pasotti , D. Giannios , M. Della Valle , A. Moretti , P. Romano , P. D'Avanzo , G. Cusumano , P. Giommi

We use RHESSI high-resolution imaging and spectroscopy observations from ~6 to 100 keV to determine the statistical relationships between measured parameters (temperature, emission measure, etc.) of hot, thermal plasma in 37 intense (GOES…

Solar and Stellar Astrophysics · Physics 2014-06-25 Amir Caspi , Säm Krucker , R. P. Lin

The imaging spectroscopy capabilities of the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) enable the examination of the accelerated electron distribution throughout a solar flare region. In particular, it has been revealed…

Solar and Stellar Astrophysics · Physics 2018-04-25 Duncan J. Stackhouse , Eduard P. Kontar

Nayakshin & Kazanas (2002) have considered the time-dependent illumination of an accretion disc in Active Galactic Nuclei, in the lamppost model. We extend their study to the flare model, which postulates the release of a large X-ray flux…

Astrophysics · Physics 2009-11-07 S. Collin , S. Coupé , A-M. Dumont , P-O. Petrucci , A. Różańska

We study the non-thermal emissions in a solar flare occurring on 2003 May 29 by using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This flare shows several typical behaviors of the HXR and microwave emissions: time delay of…

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

We examine SDO/EVE data to better understand solar flare irradiance, and how that irradiance may vary for large events. We measure scaling laws relating GOES flare classes to irradiance in 21 lines measured with SDO/EVE, formed across a…

Solar and Stellar Astrophysics · Physics 2022-03-14 Jeffrey W. Reep , David E. Siskind , Harry P. Warren

The Neupert effect is the empirical observation that the time evolution of non-thermal emission (e.g. hard X-rays) is frequently proportional to the time derivative of the thermal emission flux (soft X-rays), or, vice versa, that time…

The aim of this paper is to investigate the spatial structure of the impulsive phase hard X-ray emission from solar flares. This work is motivated by the YOHKOH and the forthcoming HESSI observations. Summarizing past results, it is shown…

Astrophysics · Physics 2009-10-31 Vahe Petrosian , Timothy Q. Donaghy

This paper investigates the temporal evolution of temperature, emission measure, energy loss and velocity in a C-class solar flare from both an observational and theoretical perspective. The properties of the flare were derived by following…

Astrophysics · Physics 2009-11-13 Claire L. Raftery , Peter T. Gallagher , Ryan O. Milligan , James A. Klimchuk

Analysis of RHESSI 3--10 keV spectra for 27 solar flares is reported. This energy range includes thermal free--free and free--bound continuum and two line features, at 6.7keV and 8keV, principally due to highly ionized iron (Fe). We used…

Astrophysics · Physics 2011-02-11 K. J. H. Phillips , C. Chifor , B. R. Dennis

Nonthermal electrons accelerated in solar flares produce electromagnetic emission in two distinct, highly complementary domains - hard X-rays (HXRs) and microwaves (MWs). This paper reports MW imaging spectroscopy observations from the…

Solar and Stellar Astrophysics · Physics 2020-04-29 Natsuha Kuroda , Gregory D. Fleishman , Dale E. Gary , Gelu M. Nita , Bin Chen , Sijie Yu