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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 statistically study the property of emerging flux regions (EFRs) and the upper solar atmosphere response to the flux emergence by using data from the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) on…

Solar and Stellar Astrophysics · Physics 2015-06-05 Jie Zhao , Hui Li

X-ray observations of the Sun led Eugene Parker to propose nanoflares as the basic energy-release units that heat the solar corona. Decades later, Solar Orbiter's Extreme Ultraviolet Imager (HRIEUV), operating halfway between Earth and the…

We use Renewal Theory for the estimation and interpretation of the flare rate from the Geostationary Operational Environmental Satellite (GOES) soft X-ray flare catalogue. It is found, that in addition to the flare rate variability with the…

Solar and Stellar Astrophysics · Physics 2015-03-20 Andrei Gorobets , Mauro Messerotti

Quasi-periodic pulsations (or QPPs) are periodic intensity variations in the flare emission, across all wavelength bands. In this paper, we review the observational and modelling achievements since the previous review on this topic by…

Solar and Stellar Astrophysics · Physics 2016-09-12 Tom Van Doorsselaere , Elena G. Kupriyanova , Ding Yuan

We have analyzed multi-wavelength observations and magnetic-field data for the solar flare of May 10, 2012 (04:18 UT) and have detected a sign inversion of the signal in the line-of-sight magnetic measurements in the umbra of a small spot.…

Solar and Stellar Astrophysics · Physics 2016-10-19 M. A. Livshits , I. Yu. Grigoryeva , I. I. Myshyakov , G. V. Rudenko

We report on the spatial relationship between solar flares and coronal mass ejections (CMEs) observed during 1996-2005 inclusive. We identified 496 flare-CME pairs considering limb flares (distance from central meridian > 45 deg) with soft…

Astrophysics · Physics 2009-11-13 S. Yashiro , G. Michalek , S. Akiyama , N. Gopalswamy , R. A. Howard

The solar group at the National Astronomical Observatory of Japan is conducting synoptic solar observations with the Solar Flare Telescope. While it is a part of a long-term solar monitoring, contributing to the study of solar dynamo…

Solar and Stellar Astrophysics · Physics 2020-09-29 Yoichiro Hanaoka , Takashi Sakurai , Ken'ichi Otsuji , Isao Suzuki , Satoshi Morita

Circular-ribbon flares (CFs) are a special type of solar flares owing to their particular magnetic topology. In this paper, we conducted a comprehensive statistical analysis of 134 CFs from 2011 September to 2017 June, including four…

Solar and Stellar Astrophysics · Physics 2022-05-25 Yanjie Zhang , Qingmin Zhang , Dechao Song , Shuting Li , Jun Dai , Zhe Xu , Haisheng Ji

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

We investigate the thermal properties of a solar flare by the observations of soft X-ray Telescope (XRT) on board Hinode and the Atmospheric Image Assembly on board the Solar Dynamics Observatory (SDO/AIA). Our analysis reveals a tenuous…

Solar and Stellar Astrophysics · Physics 2025-10-22 Xiaoyan Xie , Anna Chen , Crisel Suarez , Katharine K. Reeves , Soumya Roy , Christopher S. Moore , Nishu Karna , Joy Velasquez

Solar flares are observed and classified according to their intensity measured with the GOES X-ray Sensors. We show that the duration of a flare, as measured by the full width at half maximum (FWHM) in GOES is not related to the size of the…

Solar and Stellar Astrophysics · Physics 2019-04-10 Jeffrey W. Reep , Kalman J. Knizhnik

A common feature of electromagnetic emission from solar flares is the presence of intensity pulsations that vary as a function of time. Known as quasi-periodic pulsations (QPPs), these variations in flux appear to include periodic…

Solar and Stellar Astrophysics · Physics 2021-04-14 Brendan P. Clarke , Laura A. Hayes , Peter T. Gallagher , Shane A. Maloney , Eoin P. Carley

With the aim of understanding how the magnetic properties of active regions (ARs) control the eruptive character of solar flares, we analyze 719 flares of Geostationary Operational Environmental Satellite (GOES) class $\geq$C5.0 during…

Solar and Stellar Astrophysics · Physics 2021-09-01 Ting Li , Anqin Chen , Yijun Hou , Astrid M. Veronig , Shuhong Yang , Jun Zhang

We propose a method for diagnosing the physical conditions in the solar atmosphere using an increase in oscillation amplitudes resulting from minuscule solar flares. As an example, we consider a B2 flare, which caused a sharp short-lived…

Solar and Stellar Astrophysics · Physics 2022-01-05 Andrei Chelpanov , Nikolai Kobanov

Three-minute oscillations are a common phenomenon in the solar chromosphere above a sunspot. Oscillations can be affected by the energy release process related to solar flares. In this paper, we report on an enhanced oscillation in flare…

Solar and Stellar Astrophysics · Physics 2023-11-30 Ya Wang , Lyndsay Fletcher , Sargam Mulay , Haisheng Ji , Wenda Cao

The current sheet is an essential feature in solar flares and is the primary site for magnetic reconnetion and energy release. Imaging observations feature a long linear structure above the candle-flame-shaped flare loops, which resembles…

Solar and Stellar Astrophysics · Physics 2024-07-03 Tingyu Gou , Katharine K. Reeves

In an effort to examine the relationship between flare flux and corresponding CME mass, we temporally and spatially correlate all X-ray flares and CMEs in the LASCO and GOES archives from 1996 to 2006. We cross-reference 6,733 CMEs having…

Solar and Stellar Astrophysics · Physics 2015-05-20 Alicia N. Aarnio , Keivan G. Stassun , W. Jeffrey Hughes , Sarah L. McGregor

Flare occurrence on the Sun is highly variable, exhibiting both short term variation due to the emergence and evolution of active regions, and long-term variation from the solar cycle. On solar-like stars, much larger stellar flares…

Solar and Stellar Astrophysics · Physics 2023-01-04 James Crowley , Michael S. Wheatland , Kai Yang

We present the observations of three sympathetic filament eruptions occurring on 19 July 2015 namely F1, F2, and F3. The events were observed in UV/EUV wavelengths by Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory and…

Solar and Stellar Astrophysics · Physics 2022-04-20 Kostadinka Koleva , Pooja Devi , Ramesh Chandra , Reetika Joshi , Peter Duchlev , Momchil Dechev