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During mid-May 2024, active region (AR) 13664 produced a series of M- and X-class flares along with several coronal mass ejections (CMEs) that resulted in exceptionally strong aurora at Earth. This study presents in-situ solar energetic…

Solar flares occur due to the sudden release of energy stored in active-region magnetic fields. To date, the pre-cursors to flaring are still not fully understood, although there is evidence that flaring is related to changes in the…

Solar and Stellar Astrophysics · Physics 2012-02-01 Sophie A. Murray , D. Shaun Bloomfield , Peter T. Gallagher

Coronal elemental abundances are known to deviate from the photospheric values of their parent star, with the degree of deviation depending on the First Ionization Potential (FIP). This study focuses on the coronal composition of stars with…

Solar and Stellar Astrophysics · Physics 2015-05-13 Uria Peretz , Ehud Behar , Stephen A. Drake

We study the influence of the large-scale interplanetary magnetic field configuration on the solar energetic particles (SEPs) as detected at different satellites near Earth and on the correlation of their peak intensities with the parent…

Solar and Stellar Astrophysics · Physics 2014-03-05 R. Miteva , K. -L. Klein , O. Malandraki , G. Dorrian

{The \ion{Na}{x} X-ray lines between 10.9 and 11.2~\AA\ have attracted little attention but are of interest since they enable an estimate of the coronal abundance of Na to be made. This is of great interest in the continuing debate on the…

Solar and Stellar Astrophysics · Physics 2015-05-19 K. J. H. Phillips , K. M. Aggarwal , E. Landi , F. P. Keenan

Significant photospheric magnetic field changes during major solar eruptions -- interpreted as coronal feedback from eruptions to the photosphere -- are well-observed. However, analogous short-time scale field changes preceding eruptions…

Solar and Stellar Astrophysics · Physics 2025-12-23 Lijuan Liu , Hanzhao Yang

Shock waves associated with fast coronal mass ejections (CMEs) accelerate solar energetic particles (SEPs) in the long duration, gradual events that pose hazards to crewed spaceflight and near-Earth technological assets, but the source of…

Solar and Stellar Astrophysics · Physics 2021-03-26 David H. Brooks , Stephanie L. Yardley

Direct observations over the past four centuries show that the number of sunspots observed on the Sun's surface vary periodically, going through successive maxima and minima. Following sunspot cycle 23, the Sun went into a prolonged minimum…

Solar and Stellar Astrophysics · Physics 2013-03-05 Dibyendu Nandy , Andrés Muñoz-Jaramillo , Petrus C. H. Martens

In this study, we employ the combined charged particle measurements from Integrated Science Investigation of the Sun (\ISOIS) onboard the Parker Solar Probe (PSP) and Energetic Particle Detector (EPD) onboard the Solar Orbiter (SolO) to…

We report on the Atmospheric Imaging Assembly (AIA) observations of plasma outflows originating in a coronal dimming during the 2015 April 28th filament eruption. After the filament started to erupt, two flare ribbons formed, one of which…

Solar and Stellar Astrophysics · Physics 2021-01-20 Juraj Lörinčík , Jaroslav Dudík , Guillaume Aulanier , Brigitte Schmieder , Leon Golub

The abundance of potassium is derived from X-ray lines observed during flares by the RESIK instrument on the solar mission CORONAS-F between 3.53 A and 3.57 A. The lines include those emitted by He-like K and Li-like K dielectronic…

Solar and Stellar Astrophysics · Physics 2015-05-14 J. Sylwester , B. Sylwester , K. J. H. Phillips , V. D. Kuznetsov

Sixty years ago the first observation was published showing solar energetic particles (SEPs) with a sampling of chemical elements. Thus began study of the direct products of dynamic physics in the solar corona. As we have progressed from…

Solar and Stellar Astrophysics · Physics 2021-08-19 Donald V. Reames

Solar flares are widely accepted to be powered by magnetic reconnection that involves complex dynamics in various scales. The flare supra-arcade and loop-top region, directly impacted by fast reconnection downflows, contains a wealth of…

Solar and Stellar Astrophysics · Physics 2025-05-27 Tingyu Gou , Katharine K. Reeves

Certain solar flares exhibit a distinctive candle-flame or cusp-shaped feature above the bright flare arcade visible in extreme ultraviolet (EUV) and X-ray channels sensitive to high-temperature plasma. The presence of a cusp-like structure…

Solar and Stellar Astrophysics · Physics 2026-05-19 Ivan Oparin , Sabastian Fernandes , Bin Chen , Chengcai Shen , Xiaocan Li , Fan Guo , Sijie Yu

Plasma processes occurring in the corona and solar wind can be probed by studying the thermodynamic properties of different ion species. However, most in-situ observations of positive ions in the solar wind are taken at 1 AU, where…

Space Physics · Physics 2019-03-06 D. Stansby , D. Perrone , L. Matteini , T. S. Horbury , C. S. Salem

Shearing motion and magnetic flux cancellation around the polarity inversion line (PIL) play significant roles in the build-up of free magnetic energy and magnetic flux rope (MFR) in source region of major solar flares. Here we investigate…

Solar and Stellar Astrophysics · Physics 2026-05-12 Yijun Hou , Ting Li , Shuhong Yang , Leping Li , Yingjie Cai , Xiaofeng Liu , Shuo Yang , Yilin Guo , Shihao Rao , Chuan Li , Guiping Zhou

The second Hi-C flight (Hi-C2.1) provided unprecedentedly-high spatial and temporal resolution ($\sim$250km, 4.4s) coronal EUV images of Fe IX/X emission at 172 \AA, of AR 12712 on 29-May-2018, during 18:56:21-19:01:56 UT. Three…

The magnetic field inside the sunspot umbra, as observed by the Full-disk MagnetoGraph (FMG) onboard the Advanced Space based Solar Observatory (ASO-S), was found to be experiencing a weakening. To address this issue, we employed a method…

Solar and Stellar Astrophysics · Physics 2024-05-30 Haiqing Xu , Jiangtao Su , Suo Liu , Yuanyong Deng , Xianyong Bai , Jie Chen , Xiaofan Wang , Xiao Yang , Yongliang Song

We present observations of a B7.9-class flare that occurred on the 24th January, 2015, using the Atmopsheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO), the EUV Imaging Spectrometer (EIS) and the X-Ray Telescope of…

Solar and Stellar Astrophysics · Physics 2017-03-29 Giuseppe Nisticò , Vanessa Polito , Valery M. Nakariakov , Giulio del Zanna

Observations of the upper chromosphere shows an enormous amount of intricate fine structure. Much of this comes in the form of linear features which are most often assumed to be well aligned with the direction of the magnetic field in the…

Solar and Stellar Astrophysics · Physics 2017-10-23 Juan Martínez-Sykora , Bart De Pontieu , Mats Carlsson , Viggo Hansteen