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Extreme ultraviolet (EUV) coronal dimmings are often observed in response to solar eruptive events. These phenomena can be generated via several different physical processes. For space weather, the most important of these is the temporary…

Solar and Stellar Astrophysics · Physics 2016-10-12 James Paul Mason , Thomas N. Woods , David F. Webb , Barbara J. Thompson , Robin C. Colaninno , Angelos Vourlidas

We study the magnetic properties of small-scale transients in coronal hole. We found all brightening events are associated with bipolar regions and caused by magnetic flux emergence followed by cancellation with the pre-existing and newly…

Solar and Stellar Astrophysics · Physics 2014-05-16 Z. Huang , M. S. Madjarska , J. G. Doyle , D. A. Lamb

Magnetic-field reconnection is believed to play a fundamental role in magnetized plasma systems throughout the Universe1, including planetary magnetospheres, magnetars and accretion disks around black holes. This letter present extreme…

Solar and Stellar Astrophysics · Physics 2015-02-06 Yang Su , Astrid M. Veronig , Gordon D. Holman , Brian R. Dennis , Tongjiang Wang , Manuela Temmer , Weiqun Gan

Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent…

Relaxation of braided coronal magnetic fields through reconnection is thought to be a source of energy to heat plasma in active region coronal loops. However, observations of active region coronal heating associated with an untangling of…

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

Outflows perpendicular to the guide field are believed to be a possible signature of magnetic reconnection in the solar corona and specifically a way to detect the occurrence of ubiquitous small-angle magnetic reconnection. The aim of this…

Solar and Stellar Astrophysics · Physics 2025-03-05 G. Cozzo , P. Pagano , F. Reale , P. Testa , A. Petralia , J. Martinez-Sykora , V. Hansteen , B. De Pontieu

Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal…

Astrophysics · Physics 2007-05-23 J. Trujillo Bueno , N. Shchukina , A. Asensio Ramos

We used data from the Helioseismic and Magnetic Imager (HMI), and Atmospheric Imaging Assembly (AIA) on the \textit{Solar Dynamics Observatory} (SDO) to study coronal loops at small scales, emerging in the quiet Sun. With HMI line-of-sight…

Solar and Stellar Astrophysics · Physics 2013-04-15 LP. Chitta , R. Kariyappa , A. A. van Ballegooijen , E. E. DeLuca , S. S. Hasan , A. Hanslmeier

Superflares on the solar type stars observed by \textit{Kepler} demonstrate the contrast in the optical continuum of the order 0.1--1 per cent. The mechanism of formation of this radiation is not firmly established. We consider a model…

Solar and Stellar Astrophysics · Physics 2020-04-09 B. A. Nizamov

Context: A large number of the small and the short-lived EUV brightenings have been detected in the quiet Sun (QS) over the past three years, by the High Resolution Imager of the Extreme Ultraviolet Imager (HRIEUV) on board Solar Orbiter.…

Solar and Stellar Astrophysics · Physics 2024-08-09 A. Dolliou , S. Parenti , K. Bocchialini

By using high-resolution observations of nearly co-temporal and co-spatial Solar Optical Telescope spectropolarimeter and X-Ray Telescope coronal X-ray data onboard Hinode, we revisit the problematic relationship between global magnetic…

Solar and Stellar Astrophysics · Physics 2015-03-03 Soumitra Hazra , Dibyendu Nandy , B. Ravindra

Solar flare emission at X-ray and extreme ultraviolet (EUV) energies can cause substantial enhancements in the electron density in the Earth's lower ionosphere. It is now become clear that flares exhibit quasi-periodic pulsations with…

All cool main sequence stars including our Sun are thought to have magnetic fields. Observations of the Sun revealed that even in quiet regions small-scale turbulent magnetic fields are present. Simulations further showed that such magnetic…

Solar and Stellar Astrophysics · Physics 2023-02-01 V. Witzke , H. B. Duehnen , A. I. Shapiro , D. Przybylski , T. S. Bhatia , R. Cameron , S. K. Solanki

The coronal heating problem is one of the most critical challenges in solar physics. Recent observations have revealed that small-scale swirls are ubiquitous in the photosphere and chromosphere, suggesting that they may play a significant…

Solar and Stellar Astrophysics · Physics 2025-08-21 Hidetaka Kuniyoshi , Shinsuke Imada , Takaaki Yokoyama

Solar flares often happen after a preflare / preheating phase, which is almost or entirely thermal. In contrast, there are the so-called early impulsive flares that do not show a (significant) preflare heating but instead often show the…

Solar and Stellar Astrophysics · Physics 2018-04-04 Alexandra L. Lysenko , Alexander T. Altyntsev , Natalia S. Meshalkina , Dmitriy Zhdanov , Gregory D. Fleishman

A solar flare is composed of impulsive energy release events by magnetic reconnection, which forms and heats flare loops. Recent studies have revealed a two-phase evolution pattern of UV 1600\AA\ emission at the feet of these loops: a rapid…

Solar and Stellar Astrophysics · Physics 2013-09-16 Jiong Qiu , Zoe Sturrock , Dana W. Longcope , James A. Klimchuk , Wen-Juan , Liu

The last solar minimum has been unusually quiet compared to the previous minima (since space-based radiometric measurements are available). The Sun's magnetic flux was substantially lower during this minimum. Some studies also show that the…

Solar and Stellar Astrophysics · Physics 2015-09-02 F. Shakeri , L. Teriaca , S. K. Solanki

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…

Coronal loops are plasma structures in the solar atmosphere with temperatures reaching millions of Kelvin, shaped and sustained by the magnetic field. However, their morphology and fundamental nature remain subjects of debate. By studying…

Solar and Stellar Astrophysics · Physics 2026-01-14 N. Vasantharaju , H. Peter , L. P. Chitta , S. Mandal