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Solar flares are events of intense scientific interest. Although certain solar conditions are known to be associated with flare activity, the exact location and timing of an individual flare on the Sun cannot as yet be predicted with…

Solar and Stellar Astrophysics · Physics 2021-11-03 Andrew R. Inglis , Jack Ireland , Albert Y. Shih , Steven D. Christe

Context: Solar flare hard X-rays (HXRs) are thought to be produced by nonthermal coronal electrons stopping in the chromosphere, or remaining trapped in the corona. The collisional thick target model (CTTM) predicts that sources produced by…

Solar and Stellar Astrophysics · Physics 2015-06-15 A. O'Flannagain , P. Gallagher , J. Brown , R. Milligan , G. Holman

Iron fluorescence is produced by the irradiation of the solar photosphere by coronal X-rays during flares. This study presents the first comprehensive analysis of iron K$\alpha$ fluorescence characteristics in 47 X-class flares observed…

Soft X-ray solar bursts are studied. Weak bursts with powers up to 10-8 W/m2 were detected. All the events were confirmed by GOES observations. Parameters of these microflares are determined. A physical mechanism for the low-intensity solar…

Solar and Stellar Astrophysics · Physics 2015-09-18 I. K. Mirzoeva

The Met Office Space Weather Operations Centre was founded in 2014 and part of its remit is a daily Space Weather Technical Forecast to help the UK build resilience to space weather impacts; guidance includes four day geo-magnetic storm…

Space Physics · Physics 2018-04-10 Michael A. Sharpe , Sophie A. Murray

Solar flares originate from magnetically active regions but not all solar active regions give rise to a flare. Therefore, the challenge of solar flare prediction benefits by an intelligent computational analysis of physics-based properties…

Solar and Stellar Astrophysics · Physics 2019-10-09 Cristina Campi , Federico Benvenuto , Anna Maria Massone , D Shaun Bloomfield , Manolis K Georgoulis , Michele Piana

We study the energy release process of a set of 51 flares (32 confined, 19 eruptive) ranging from GOES class B3 to X17. We use H$\alpha$ filtergrams from Kanzelh\"ohe Observatory together with SDO HMI and SOHO MDI magnetograms to derive…

Solar and Stellar Astrophysics · Physics 2018-02-07 Johannes Tschernitz , Astrid M. Veronig , Julia K. Thalmann , Jürgen Hinterreiter , Werner Pötzi

Archived high-resolution X-ray spectra in the 13~\AA\ to 22~\AA\ range from the Flat Crystal Spectrometer (FCS), an instrument on the Solar Maximum Mission operating in the 1980s, are analyzed with reference to nonflaring active regions,…

Solar and Stellar Astrophysics · Physics 2026-01-27 Kenneth J. H. Phillips , Barbara Sylwester , Janusz Sylwester

We present the first results using the Reuven Ramaty High-Energy Solar Spectroscopic Imager, RHESSI, to observe solar X-ray emission not associated with active regions, sunspots or flares (the quiet Sun). Using a newly developed chopping…

Astrophysics · Physics 2008-11-26 Iain G. Hannah , G. J Hurford , H. S. Hudson , R. P. Lin , K. van Bibber

The Solar Low-Energy X-ray Spectrometer (SoLEXS) on board India's Aditya-L1 mission was launched on 2 September 2023 and commenced solar observations on 13 December 2023 following successful aperture cover deployment. Operating from the…

Studies in the extreme ultraviolet (EUV) and X-ray ranges of the solar spectrum are important due to the active role of radiation of these ranges in the formation of the Earth's ionosphere. Photons of the EUV range are completely absorbed…

Solar and Stellar Astrophysics · Physics 2019-12-24 E. A. Bruevich , G. V. Yakunina

In this paper, the energy budgets of two single-loop like flares observed in X- ray are analysed under the assumption that non-thermal electrons (NTEs) are the only source of plasma heating during all phases of both events. The flares were…

Solar and Stellar Astrophysics · Physics 2014-06-19 R. Falewicz

In order to study the acceleration and propagation of bremsstrahlung-producing electrons in solar flares, we analyze the evolution of the flare loop size with respect to energy at a variety of times. A GOES M3.7 loop-structured flare…

Solar and Stellar Astrophysics · Physics 2015-06-05 Jingnan Guo , A. Gordon Emslie , Eduard P. Kontar , Federico Benvenuto , Anna Maria Massone , Michele Piana

We present an alternate method of determining the progression of the solar cycle through an analysis of the solar X-ray background. Our results are based on the NOAA Geostationary Operational Environmental Satellites (GOES) X-ray data in…

Solar and Stellar Astrophysics · Physics 2015-06-22 L. M. Winter , K. S. Balasubramaniam

The Dual-zone Aperture X-ray Solar Spectrometer (DAXSS) was flown on 2018 June18 on the NASA 36.336 sounding rocket flight and obtained the highest resolution to date for solar soft X-ray (SXR) spectra over a broad energy range. This…

Solar and Stellar Astrophysics · Physics 2020-11-24 Bennet D. Schwab , Robert H. A. Sewell , Thomas N. Woods , Amir Caspi , James Paul Mason , Christopher Moore

Foundation models offer a promising route to transferable remote sensing representations, but many current approaches depend on very large pretraining datasets and fixed sensor configurations, limiting their suitability for ecological and…

Measuring the relative amount of high-temperature, low-emission-measure plasma is considered to be a smoking gun observation to constrain the frequency of plasma heating in coronal structures. Often, narrowband, extreme ultraviolet images,…

Solar and Stellar Astrophysics · Physics 2024-01-24 P. S. Athiray , Amy R. Winebarger

The radio emission during 201 X-ray selected solar flares was surveyed from 100 MHz to 4 GHz with the Phoenix-2 spectrometer of ETH Zurich. The selection includes all RHESSI flares larger than C5.0 jointly observed from launch until June…

Astrophysics · Physics 2009-11-10 Arnold O. Benz , Paolo Grigis , Andre Csillagy , Pascal Saint-Hilaire

We apply multi-algorithm machine learning models to TESS 2-minute survey data from Sectors 1-72 to identify stellar flares. Models trained with Deep Neural Network, Random Forest, and XGBoost algorithms, respectively, utilized four flare…

Solar and Stellar Astrophysics · Physics 2024-10-24 Chia-Lung Lin , Daniel Apai , Mark S. Giampapa , Wing-Huen Ip

Solar flares produce radiation which can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The number of published approaches to flare…