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The GOES X1.5 class flare that occurred on August 30,2002 at 1327:30 UT is one of the few events detected so far at submillimeter wavelengths. We present a detailed analysis of this flare combining radio observations from 1.5 to 212 GHz (an…

Solar and Stellar Astrophysics · Physics 2015-05-13 C. G. Gimenez de Castro , G. Trottet , A. Silva-Valio , S. Krucker , J. E. R. Costa , P. Kaufmann , E. Correia , H. Levato

Solar-type stars have been observed to flare at optical wavelengths to energies much higher than observed for the Sun. To date, no counterparts have been observed at longer wavelengths. We have searched the the VLA Sky Survey (VLASS) for…

Solar and Stellar Astrophysics · Physics 2024-08-28 Ivey Davis , Gregg Hallinan , Carlos Ayala , Dillon Dong , Steven Myers

In this work, we studied X-ray source SRGe~J021932.4$-$040154 (SRGe J021932), which we associated with a single X-ray active star of spectral class G2V-G4V and the rotational period $\rm P_{rot} < 9.3$ days. Additional analysis of TESS…

High Energy Astrophysical Phenomena · Physics 2024-12-13 Andrey Mukhin , Roman Krivonos , Ilfan Bikmaev , Mark Gorbachev , Irek Khamitov , Sergey Sazonov , Marat Gilfanov , Rashid Sunyaev

Aims: This paper aims to demonstrate the importance of short-exposure extreme ultraviolet (EUV) observations of solar flares in the study of particle acceleration, heating and energy partition in flares. This work highlights the…

White-light flares (WLFs) are crucial for understanding the energy transport and heating processes in the lower solar atmosphere. Systematic studies are highly necessary. However, most WLFs are very weak and difficult to detect. To address…

Solar and Stellar Astrophysics · Physics 2026-04-15 Shuanghong Li , Yongliang Song , Kun Wang , Xianyong Bai , Xiao Yang , Nian Liu , Ziyao Hu

Stellar flares have been extensively studied in soft X-rays (SXR) by basically every X-ray mission. Hard X-ray (HXR) emission from stellar superflares, however, have only been detected from a handful of objects over the past years. One very…

High Energy Astrophysical Phenomena · Physics 2017-12-20 Stefan Ohm , Clemens Hoischen

Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim to understand the magnetic properties that govern such flares and eruptions, we systematically survey all flare…

Solar and Stellar Astrophysics · Physics 2017-01-11 Shin Toriumi , Carolus J. Schrijver , Louise K. Harra , Hugh Hudson , Kaori Nagashima

A M-class behind-the-limb solar flare on 1 May 2013 (SOL2013-05-01T02:32), accompanied by a ($\sim$ 400 km/s) CME was observed by several space-based observatories with different viewing angles. We investigated the RHESSI-observed occulted…

We investigate accelerated electron energy spectra for different sources in a large flare using simultaneous observations obtained with two instruments, the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz, and the Reuven Ramaty High…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. R. Kundu , V. V. Grechnev , S. M. White , E. J. Schmahl , N. S. Meshalkina , L. K. Kashapova

Observations relating the characteristics of electrons seen near Earth (SEPs) and those producing flare radiation show that in certain (prompt) events the origin of both population appears to be the flare site, which show strong correlation…

Solar and Stellar Astrophysics · Physics 2016-10-12 Vahe' Petrosian

We present a search for stellar activity (flares and mass ejections) in a sample of 28 stars in the young open cluster Blanco-1. We use optical spectra obtained with ESO's VIMOS multi-object spectrograph installed on the VLT. From the total…

Solar and Stellar Astrophysics · Physics 2015-06-19 M. Leitzinger , P. Odert , R. Greimel , H. Korhonen , E. W. Guenther , A. Hanslmeier , H. Lammer , M. L. Khodachenko

Around the peaks of substantial flares, bright artifact nearly horizontal saturation streaks (B-streaks) corresponding to the brightest parts of the flare sources appear in the STEREO/EUVI 195 A images. We show that the length of such…

Solar and Stellar Astrophysics · Physics 2015-08-06 I. M. Chertok , A. V. Belov , V. V. Grechnev

We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active…

We present results on spectroscopic observations of the fast-rotating active giant FK Comae, obtained mainly with the ESA-MUSICOS spectrograph at the Isaac Newton Telescope (INT) in 1996 and 1997 and also with the Aurelie spectrograph at…

Astrophysics · Physics 2007-05-23 J. M. Oliveira , B. H. Foing

White-light stellar flares are now reported by the thousands in long-baseline, high precision, broad-band photometry from missions like Kepler, K2, and TESS. These observations are crucial inputs for assessments of biosignatures in…

Solar and Stellar Astrophysics · Physics 2022-11-01 Adam F. Kowalski

The energy in the solar acoustic spectrum is known to be correlated with flares, but it is not known if the same is true for stellar flares? In order to answer this question, we have analyzed 73 flares in 39 solar-like stars. These flares…

Solar and Stellar Astrophysics · Physics 2015-06-18 C. Karoff

We develop a new and powerful method to analyze time series to rigorously detect flares in the presence of an irregularly oscillatory baseline, and apply it to stellar light curves observed with TESS. First, we remove the underlying…

Solar and Stellar Astrophysics · Physics 2025-12-23 Qiyuan Wang , Giovanni Motta , Genaro Sucarrat , Vinay L. Kashyap

We present the temporal and spectral study of blazar PKS 0208-512, using recent flaring activity from November 2019 to May 2020, as detected by the Fermi-LAT observatory. The contemporaneous X-ray, optical/UV observations from…

High Energy Astrophysical Phenomena · Physics 2022-07-12 Rukaiya Khatoon , Raj Prince , Zahir Shah , Sunder Sahayanathan , Rupjyoti Gogoi

Solar flares stronger than X10 (S-flares, >X10) are the highest class flares which significantly impact on the Sun's evolution and space weather. Based on observations of Geostationary Orbiting Environmental Satellites (GOES) at soft X-ray…

Solar and Stellar Astrophysics · Physics 2025-01-10 Baolin Tan , Yin Zhang , Jing Huang , Kaifan Ji

A popular scenario for electron acceleration in solar flares is transit-time damping of low-frequency MHD waves excited by reconnection and its outflows. The scenario requires several processes in sequence to yield energetic electrons of…

Astrophysics · Physics 2015-06-24 Arnold O. Benz , Pascal Saint-Hilaire
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