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Spectroscopic observations in X-ray wavelengths provide excellent diagnostics of the temperature distribution in solar flare plasma. The Solar X-ray Monitor (XSM) onboard the Chandrayaan-2 mission provides broad-band disk integrated soft…

We investigate the influence of the variations of energy spectrum of non-thermal electrons on the resulting GOES classes of solar flares. Twelve observed flares with various soft to hard X-ray emission ratios were modelled using different…

Solar and Stellar Astrophysics · Physics 2009-09-25 R. Falewicz , P. Rudawy , M. Siarkowski

We investigate the X-ray and UV emission detected by RHESSI and TRACE in the context of a solar flare on the 16th November 2002 with the goal of better understanding the evolution of the flare. We analysed the characteristics of the X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-11 Hamish A. S. Reid , Nicole Vilmer , Guillaume Aulanier , Etienne Pariat

We report hard X-ray and gamma-ray observations of the impulsive phase of the SOL2017-09-06T11:55 X9.3 solar flare. We focus on a high-energy part of the spectrum, >100 keV, and perform time resolved spectral analysis for a portion of the…

High Energy Astrophysical Phenomena · Physics 2019-06-11 Alexandra L. Lysenko , Sergey A. Anfinogentov , Dmitry D. Svinkin , Dmitry D. Frederiks , Gregory D. Fleishman

We report solar flare plasma to be multi-thermal in nature based on the theoretical model and study of the energy-dependent timing of thermal emission in ten M-class flares. We employ high-resolution X-ray spectra observed by the Si…

Solar and Stellar Astrophysics · Physics 2011-03-30 Rajmal Jain , Arun Kumar Awasthi , Arvind Singh Rajpurohit , Markus J. Aschwanden

Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic…

Solar and Stellar Astrophysics · Physics 2016-02-15 W. G. Fajardo-Mendieta , J. C. Martínez-Oliveros , J. D. Alvarado-Gómez , B. Calvo-Mozo

The Fermi Large Area Telescope (LAT) observed two bright X-class solar flares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission…

High Energy Astrophysical Phenomena · Physics 2017-02-22 LAT collaboration

A large arcade flare of 2 March 1993 has been investigated using X-ray observations recorded by the {\sl Yohkoh} and GOES satellites and the {\sl Compton Gamma Ray Observatory}. We analyzed quasi-periodicity of the hard-X-ray (HXR) pulses…

Solar and Stellar Astrophysics · Physics 2015-06-18 Jerzy Jakimiec , Michal Tomczak

Based on a sample of 1114 flares observed simultaneously in hard X-rays (HXR) by the BATSE instrument and in soft X-rays (SXR) by GOES, we studied several aspects of the Neupert effect and its interpretation in the frame of the…

Astrophysics · Physics 2009-11-07 A. Veronig , B. Vrsnak , B. R. Dennis , M. Temmer , A. Hanslmeier , J. Magdalenic

We develop the impulsiveness index, a new classification system for solar flares using the SDO/EVE 304 {\AA} Sun-as-a-star light curves. Impulsiveness classifies events based on the duration and intensity of the initial high-energy…

Solar and Stellar Astrophysics · Physics 2024-03-06 Cole A Tamburri , Maria D Kazachenko , Adam F Kowalski

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

Investigate particle acceleration and heating in a solar microflare. In a microflare with non-thermal emission to remarkably high energies ($>50$ keV), we investigate the hard X-rays with RHESSI imaging and spectroscopy and the resulting…

Astrophysics · Physics 2010-09-17 I. G. Hannah , S. Krucker , H. S. Hudson , S. Christe , R. P. Lin

Context: Solar flares release a large fraction of their energy into non-thermal electrons, but it is not clear where and how. Bremsstrahlung X-rays are observed from the corona and chromosphere. Aims: We aim to characterize the acceleration…

Astrophysics · Physics 2009-11-11 Marina Battaglia , Arnold O. Benz

Most theoretical investigations of particle acceleration during solar flares cannot be applied to observations for detailed study of the time evolution. We propose a phenomenological model for turbulence evolution and stochastic particle…

Solar and Stellar Astrophysics · Physics 2009-08-10 Siming Liu , Lyndsay Fletcher

Aims. In this paper, we investigate the temporal evolution and north-south (N-S) asymmetry in the occurrence of solar flares during cycle 21, 22, and 23, and compare the results with traditional solar activity indices. Methods. The flare…

Solar and Stellar Astrophysics · Physics 2017-05-08 Bhuwan Joshi , R. Bhattacharyya , K. K. Pandey , Upendra Kushwaha , Yong-Jae Moon

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

Solar flares are sudden energy release events in the solar corona, resulting from magnetic reconnection, that accelerates particles and heats the ambient plasma. During a flare, there are often multiple, temporally and spatially separated…

Solar and Stellar Astrophysics · Physics 2020-12-02 Rohit Sharma , Marina Battaglia , Yingjie Luo , Bin Chen , Sijie Yu

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…

A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES…

Solar and Stellar Astrophysics · Physics 2016-01-20 Matej Kuhar , Säm Krucker , Juan Carlos Martínez Oliveros , Marina Battaglia , Lucia Kleint , Diego Casadei , Hugh S. Hudson

In this study we present the analysis of six solar flare events that occurred in 2022, using new data from the third-generation Miniature X-Ray Solar Spectrometer (MinXSS), also known as the Dual-zone Aperture X-ray Solar Spectrometer…

Solar and Stellar Astrophysics · Physics 2024-03-12 Anant Telikicherla , Thomas N. Woods , Bennet D. Schwab