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Related papers: The existence of hot X-ray onsets in solar flares

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The study of the localized plasma conditions before the impulsive phase of a solar flare can help us understand the physical processes that occur leading up to the main flare energy release. Here, we present evidence of a hot X-ray onset…

Solar and Stellar Astrophysics · Physics 2020-12-02 Hugh S. Hudson , Paulo J. A. Simoes , Lyndsay Fletcher , Laura A. Hayes , Iain G. Hannah

Understanding the physical processes that trigger solar flares is paramount to help with forecasting space weather and mitigating the effects on our technological infrastructure. A previously unknown phenomenon was recently identified in…

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

We present analysis of a GOES C1-class flare from 2022 September 6, which was jointly observed as occulted by Nuclear Spectroscopic Telescope ARray (NuSTAR) and on-disk by Spectrometer/Telescope for Imaging X-rays (STIX). NuSTAR observed…

In this paper we analyze soft and hard X-ray emission of the 2002 September 20 M1.8 GOES class solar flare observed by RHESSI and GOES satellites. In this flare event, soft X-ray emission precedes the onset of the main bulk hard X-ray…

Solar and Stellar Astrophysics · Physics 2014-11-20 M. Siarkowski , R. Falewicz , P. Rudawy

This study investigates the statistical behavior of plasma properties during Hot Onset Precursor Events (HOPEs) of solar flares and evaluates their potential for improving flare nowcasting. Two datasets are analyzed: (a) new Soft X-Ray…

Solar and Stellar Astrophysics · Physics 2025-09-08 Anant Telikicherla , Thomas N. Woods , Bennet D. Schwab

The light curves of solar flares in the impulsive phase are complex in general, indicating that multiple physical processes are involved in. With the GOES (Geostationary Operational Environmental Satellite) observations, we find that there…

Solar and Stellar Astrophysics · Physics 2015-06-16 HAN , Fei-ran , LIU , Si-ming

The Sun offers a convenient nearby laboratory to study the physical processes of particle acceleration and impulsive energy release in magnetized plasmas that occur throughout the universe, from planetary magnetospheres to black hole…

Solar and Stellar Astrophysics · Physics 2011-05-13 Amir Caspi

Non-thermal velocities, derived from spectral line broadening, can provide crucial insights into plasma dynamics before and during solar flares. To systematically study the pre-flare phase, we constructed a Hinode/Extreme-ultraviolet…

During its commissioning phase in 2020, the Spectrometer/Telescope for Imaging X-rays (STIX) on board the Solar Orbiter spacecraft observed 69 microflares. The two most significant events from this set (of GOES class B2 and B6) were…

Solar and Stellar Astrophysics · Physics 2022-03-14 J. Saqri , A. M. Veronig , A. Warmuth , E. C. M. Dickson , A. F. Battaglia , T. Podladchikova , H. Xiao , M. Battaglia , G. J. Hurford , S. Krucker

Spectroscopic analysis of large flares (>X1) in the hard X-ray (HXR) range offers unique insights into the hottest (> 30 MK) flare plasma, the so-called superhot thermal component. To manage the high count rates in large flares, an…

Solar and Stellar Astrophysics · Physics 2026-02-11 Muriel Zoë Stiefel , Natália Bajnoková , Säm Krucker

Solar flares commonly have a hot onset precursor event" (HOPE), detectable from soft X-ray observations. Detecting this requires subtraction of pre-flare fluxes from the non-flaring Sun prior to the event, fitting an isothermal emission…

Solar and Stellar Astrophysics · Physics 2024-07-08 Hugh S. Hudson

We present a case study of an M4-class flare on 28 March 2022, near Solar Orbiter's first science perihelion (0.33 AU). Solar Orbiter was 83.5{\deg} west of the Sun-Earth line, making the event appear near the eastern limb, while…

The timing of 503 solar flares observed simultaneously in hard X-rays, soft X-rays and H-alpha is analyzed. We investigated the start and the peak time differences in different wavelengths, as well as the differences between the end of the…

Astrophysics · Physics 2015-06-24 A. Veronig , B. Vrsnak , M. Temmer , A. Hanslmeier

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

We investigate two microflares of GOES classes A9 and C1 (after background subtraction) observed by STIX onboard Solar Orbiter with exceptionally strong nonthermal emission. We complement the hard X-ray imaging and spectral analysis by STIX…

Solar and Stellar Astrophysics · Physics 2024-03-12 Jonas Saqri , Astrid M. Veronig , Andrea Francesco Battaglia , Ewan C. M. Dickson , Dale E. Gary , Säm Krucker

Solar flares often happen after a preflare / preheating phase, which is almost or entirely thermal. In contrast, there are the so-called early impulsive flares that do not show a (significant) preflare heating but instead often show the…

Solar and Stellar Astrophysics · Physics 2018-04-04 Alexandra L. Lysenko , Alexander T. Altyntsev , Natalia S. Meshalkina , Dmitriy Zhdanov , Gregory D. Fleishman

Solar eruptive events, including solar flares and coronal mass ejections (CMEs), are typically characterised by energetically significant X-ray emissions from flare-accelerated electrons and hot thermal plasmas. Occulted events, where the…

Solar and Stellar Astrophysics · Physics 2024-11-13 Laura A. Hayes , Säm Krucker , Hannah Collier , Daniel Ryan

One of the main science questions of the Solar Orbiter and Parker Solar Probe missions deals with understanding how electrons in the lower solar corona are accelerated and how they subsequently access interplanetary space. We aim to…

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