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Context: Photospheric flows create a network of often mixed-polarity magnetic field in the quiet Sun, where small-scale eruptions and network flares are commonly seen. Aims: The aim of this paper is (1) to describe the characteristics of…

Solar and Stellar Astrophysics · Physics 2017-05-31 R. Attie , D. E. Innes , S. K. Solanki , K. H. Glassmeier

We present the results of a search of the XMM-Newton public data archive for stellar X-ray flares. We find eight flaring sources for which we identify 7 optical counterparts. Three of these sources have distance estimates which allow us to…

Astrophysics · Physics 2009-11-10 Duncan Trenholme , Gavin Ramsay , Carl Foley

We use high spatial and temporal resolution observations from the Swedish Solar Telescope to study the chromospheric velocities of a C-class flare originating from active region NOAA 10969. A time-distance analysis is employed to estimate…

Solar and Stellar Astrophysics · Physics 2015-05-27 Peter H. Keys , David B. Jess , Mihalis Mathioudakis , Francis P. Keenan

On April 23, 2014, the Swift satellite responded to a hard X-ray transient detected by its Burst Alert Telescope, which turned out to be a stellar flare from a nearby, young M dwarf binary DG~CVn. We utilize observations at X-ray, UV,…

Flares close to the solar limb, where the footpoints are occulted, can reveal the spectrum and structure of the coronal loop-top source in X-rays. We aim at studying the properties of the corresponding energetic electrons near their…

We investigate quasi-periodic coronal pulsations during the decay phase of an X 3.2 class flare on 14 May 2013, using soft X-ray data from the RHESSI satellite. Periodogram analyses of soft X-ray light curves show that 53 s and 72 s periods…

Solar and Stellar Astrophysics · Physics 2016-01-20 Partha Chowdhury , A. K. Srivastava , B. N. Dwivedi , Robert Sych , Y. -J. Moon

The solar X-ray irradiance is significantly heightened during the course of a solar flare, which can cause radio blackouts due to ionization of the atoms in the ionosphere. As the duration of a solar flare is not related to the size of that…

Solar and Stellar Astrophysics · Physics 2021-11-10 Jeffrey W. Reep , Will T. Barnes

We derive the minimum observing time scales to detect a blazar at a given flux level with the LAT on GLAST in the scanning and pointing modes. Based upon Phase 1 observations with EGRET, we predict the GLAST detection rate of blazar flares…

Astrophysics · Physics 2009-11-10 C. D. Dermer , B. L. Dingus

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

We describe a new tool developed for solar flare forecasting on the base of some sunspot group properties. Assuming that the flare frequency follows the Poisson statistics, this tool uses a database containing the morphological…

Solar and Stellar Astrophysics · Physics 2019-05-16 M. Falco , P. Costa , P. Romano

In the standard model, magnetic reconnection at a vertical current sheet above the flare arcade is key to explaining many aspects of solar eruptions. The supra-arcade region is where the vertical current sheet is supposedly located, and…

Solar and Stellar Astrophysics · Physics 2025-12-23 Hanya Pan , Astrid M. Veronig , Rui Liu

Solar active region 12673 produced two successive X-class flares (X2.2 and X9.3) approximately 3 hours apart in September 2017. The X9.3 was the recorded largest solar flare in Solar Cycle 24. In this study we perform a data-constrained…

Solar and Stellar Astrophysics · Physics 2021-06-23 Satoshi Inoue , Yumi Bamba

Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24, we explored 100 active regions (ARs) that produced M5.0 or stronger flares. We focus on the presence/absence of the emergence of magnetic flux in…

Solar and Stellar Astrophysics · Physics 2024-02-29 Alexander S. Kutsenko , Valentina I. Abramenko , Andrei A. Plotnikov

We report on the results of our simultaneous observations of three large stellar flares with soft X-rays (SXRs) and an H$\mathrm{\alpha}$ emission line from two binary systems of RS CVn type. The energies released in the X-ray and…

High Energy Astrophysical Phenomena · Physics 2023-07-06 Hiroki Kawai , Yohko Tsuboi , Wataru B. Iwakiri , Yoshitomo Maeda , Satoru Katsuda , Ryo Sasaki , Junya Kohara , MAXI TEAM

Sun-as-a-star spectroscopic characteristics of solar flares can be used as a benchmark for the detection and analyses of stellar flares. Here, we study the Sun-as-a-star properties of an X1.0 solar flare using high-resolution spectroscopic…

Solar and Stellar Astrophysics · Physics 2024-03-15 Y. L. Ma , Q. H. Lao , X. Cheng , B. T. Wang , Z. H. Zhao , S. H. Rao , C. Li , M. D. Ding

This study explores the behavior of machine learning-based flare forecasting models deployed in a simulated operational environment. Using Georgia State University's Space Weather Analytics for Solar Flares benchmark dataset (Angryk et al.…

Solar and Stellar Astrophysics · Physics 2024-02-09 Griffin T. Goodwin , Viacheslav M. Sadykov , Petrus C. Martens

Gamma-ray burst X-ray flares are believed to mark the late time activity of the central engine. We compute the temporal evolution of the average flare luminosity $< L >$ in the common rest frame energy band of 44 GRBs taken from the large…

High Energy Astrophysical Phenomena · Physics 2015-05-19 R. Margutti , G. Bernardini , R. Barniol Duran , C. Guidorzi , R. F. Shen , G. Chincarini

We present a case study of solar flare forecasting by means of metadata feature time series, by treating it as a prominent class-imbalance and temporally coherent problem. Taking full advantage of pre-flare time series in solar active…

Solar and Stellar Astrophysics · Physics 2021-05-26 Azim Ahmadzadeh , Berkay Aydin , Manolis K. Georgoulis , Dustin J. Kempton , Sushant S. Mahajan , Rafal A. Angryk

In this paper, we discuss the temperature distribution and evolution of a microflare, simultaneously observed by Hinode XRT, EIS, and SDO AIA. We find using EIS lines that during peak emission the distribution is nearly isothermal and…

Solar and Stellar Astrophysics · Physics 2019-08-21 Urmila Mitra-Kraev , Giulio Del Zanna

Solar flare forecasting research using machine learning (ML) has focused on high resolution magnetogram data from the SDO/HMI era covering Solar Cycle 24 and the start of Solar Cycle 25, with some efforts looking back to SOHO/MDI for data…

Solar and Stellar Astrophysics · Physics 2023-08-30 Kiera van der Sande , Andrés Muñoz-Jaramillo , Subhamoy Chatterjee
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