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Extreme-ultraviolet images from the Solar Dynamics Observatory often show looplike fine structure to be present where no minority-polarity flux is visible in magnetograms, suggesting that the rate of ephemeral region (ER) emergence inside…

Solar and Stellar Astrophysics · Physics 2021-04-14 Y. -M. Wang

Solar nanoflares are small eruptive events releasing magnetic energy in the quiet corona. If nanoflares follow the same physics as their larger counterparts, they should emit hard X-rays (HXRs) but with a rather faint intensity. A copious…

Small-scale brightenings in solar atmospheric observations are a manifestation of heating and/or energy transport events. We present statistical characteristics of brightenings from a new detection method applied to 1330, 1400, and 2796…

Solar and Stellar Astrophysics · Physics 2021-10-01 Llŷr Dafydd Humphries , Huw Morgan

X-ray and EUV observations are an important diagnostic of various plasma parameters of the solar atmosphere during solar flares. Soft X-ray and EUV observations often show coronal sources near the top of flaring loops, while hard X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-11 Marina Battaglia , Eduard P. Kontar

On April 17, 2024, the third successful Hi-C sounding rocket flight, Hi-C Flare, recorded coronal images in Fe XXI 129 A emission from 11 MK plasma during the post-maximum phase of an M1.6-class solar flare, achieving unprecedented spatial…

The characterization of exoplanets, their formation, evolution, and chemical changes is tightly linked to our knowledge of their host stars. In particular, stellar X-rays and UV emission have a strong impact on the dynamical and chemical…

Solar and Stellar Astrophysics · Physics 2022-04-20 I. Pillitteri , G. Micela , A. Maggio , S. Sciortino , J. Lopez-Santiago

We present the analysis of a compact flare that occurred on 2002/02/26 at 10:26 UT, seen by both RHESSI and TRACE. The size of the nearly circular hard X-ray source is determined to be 4.7(+-1.5)" from the modulation profiles of the RHESSI…

Astrophysics · Physics 2009-11-07 P. Saint-Hilaire , A. O. Benz

Context. Recent observations by the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have characterized prevalent small-scale transient brightenings in the corona above the quiet Sun termed campfires. Aims. In this study we search…

Solar and Stellar Astrophysics · Physics 2021-12-15 Yajie Chen , Damien Przybylski , Hardi Peter , Hui Tian , F. Auchère , D. Berghmans

Ground- and space-based observations of solar flares from radio wavelengths to gamma-rays have produced considerable insights but raised several unsolved controversies. The last unexplored wavelength frontier for solar flares is in the…

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…

The EUI instrument on the Solar Orbiter spacecraft has obtained the most stable, high-resolution images of the solar corona from its orbit with a perihelion near 0.4 AU. A sequence of 360 images obtained at 17.1 nm, between 25-Oct-2022…

Solar and Stellar Astrophysics · Physics 2023-09-12 Philip G. Judge

Solar pores are strongly magnetized regions lacking a photospheric penumbra and characterized by predominantly vertical magnetic fields. We present a multi-line study of flashes in a solar pore using high-resolution observations from the…

Solar and Stellar Astrophysics · Physics 2026-02-11 Sandeep Dubey , Christian Beck , Rahul Yadav , Tobias Felipe , Shibu K Mathew

We present the result of comparison between magnetic field parameters and the intensity of X-ray emission for solar microflares with Geosynchronous Operational Environmental Satellites (GOES) classes from A0.02 to B5.1. For our study, we…

Solar and Stellar Astrophysics · Physics 2017-08-30 A. S. Kirichenko , S. A. Bogachev

Minifilament (MF) eruption producing small jets and micro-flares is regarded as an important source for coronal heating and the solar wind transients through studies mostly based on coronal observations in the extreme ultraviolet (EUV) and…

Solar and Stellar Astrophysics · Physics 2024-02-14 Jiasheng Wang , Jeongwoo Lee , Jongchul Chae , Yan Xu , Wenda Cao , Haimin Wang

Solar flare ribbon fronts appear ahead of the bright structures that normally characterise solar flares, and can persist for an extended period of time in spatially localised patches before transitioning to `regular' bright ribbons. They…

Solar and Stellar Astrophysics · Physics 2024-05-07 Graham S. Kerr , Vanessa Polito , Yan Xu , Joel C. Allred

The precise physical process that triggers solar flares is not currently understood. Here we attempt to capture the signature of this mechanism in solar image data of various wavelengths and use these signatures to predict flaring activity.…

Solar and Stellar Astrophysics · Physics 2018-03-14 Eric Jonas , Monica G. Bobra , Vaishaal Shankar , J. Todd Hoeksema , Benjamin Recht

Superflares on solar-type stars has been a rapidly developing field ever since the launch of $\it Kepler$. Over the years, there have been several studies investigating the statistics of these explosive events. In this study, we present a…

Solar and Stellar Astrophysics · Physics 2020-04-22 Lauren Doyle , Gavin Ramsay , J. Gerard Doyle

Coronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively-driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these…

Solar and Stellar Astrophysics · Physics 2023-03-01 William Ashfield , Dana Longcope

A challenge in characterizing active region (AR) coronal heating is in separating transient (bursty) loop heating from the diffuse background (steady) heating. We present a method of quantifying coronal heating's bursty and steady…

Solar and Stellar Astrophysics · Physics 2023-01-04 Sanjiv K. Tiwari , Lucy A. Wilkerson , Navdeep K. Panesar , Ronald L. Moore , Amy R. Winebarger

We report the discovery of fast (~ 100 sec) 2.2 micron flares from the microquasar GRS 1915+105, which are superimposed on longer (~ 30 min), brighter flares corresponding to episodes of jet formation. The number and strength of the…

Astrophysics · Physics 2007-05-23 David M. Rothstein , Stephen S. Eikenberry