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On 2016 September 20, the Interface Region Imaging Spectrograph observed an active region during its earliest emerging phase for almost 7 hours. The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory observed…

Solar and Stellar Astrophysics · Physics 2018-03-14 Hui Tian , Xiaoshuai Zhu , Hardi Peter , Jie Zhao , Tanmoy Samanta , Yajie Chen

Coronal waves exist ubiquitously in the solar atmosphere. They are important not only in their own rich physics but also essential candidates of triggering magnetic eruptions in the remote. However, the later mechanism has never been…

Solar and Stellar Astrophysics · Physics 2021-01-06 Guiping Zhou , Guannan Gao , Jingxiu Wang , Jun Lin , Yingna Su , Chunlan Jin , Yuzong Zhang

Turbulent plasma motion is common in the universe, and invoked in solar flares to drive effective acceleration leading to high energy electrons. Unresolved mass motions are frequently detected in flares from extreme ultraviolet (EUV)…

Solar and Stellar Astrophysics · Physics 2023-05-03 Wenzhi Ruan , Limei Yan , Rony Keppens

Magnetic reconnection plays a crucial role in the energy release process for different kinds of solar eruptions and activities. The rapid solar eruption requires a fast reconnection model. Plasmoid instability in the reconnecting current…

Solar and Stellar Astrophysics · Physics 2024-05-01 Guanchong Cheng , Lei Ni , Zehao Tang , Yajie Chen , Yuhao Chen , Jialiang Hu , Jun Lin

A small flare ribbon above a sunspot umbra in active region 12205 was observed on November 7, 2014, at 12:00 UT in the blue imaging channel of the 1.5 m GREGOR telescope, using a 1 A Ca II H interference filter. Context observations from…

Disconnection of open magnetic flux by reconnection is required to balance the injection of open flux by CMEs and other eruptive events. Making use of recent advances in heliospheric background subtraction, we have imaged many abrupt…

Solar and Stellar Astrophysics · Physics 2015-06-03 C. E. DeForest , T. A. Howard , D. J. McComas

White-light flares (WLFs), first observed in 1859, refer to a type of solar flares showing an obvious enhancement of the visible continuum emission. This type of enhancement often occurs in most energetic flares, and is usually interpreted…

Solar and Stellar Astrophysics · Physics 2020-04-22 Yongliang Song , Hui Tian , Xiaoshuai Zhu , Yajie Chen , Mei Zhang , Jingwen Zhang

Magnetic reconnection plays a crucial role in powering solar flares, production of energetic particles, and plasma heating. However, where the magnetic reconnections occur, how and where the released magnetic energy is transported, and how…

Solar and Stellar Astrophysics · Physics 2020-09-02 Sijie Yu , Bin Chen , Katharine K. Reeves , Dale E. Gary , Sophie Musset , Gregory D. Fleishman , Gelu M. Nita , Lindsay Glesener

Solar flares are sudden energy release events in the solar corona, resulting from magnetic reconnection, that accelerates particles and heats the ambient plasma. During a flare, there are often multiple, temporally and spatially separated…

Solar and Stellar Astrophysics · Physics 2020-12-02 Rohit Sharma , Marina Battaglia , Yingjie Luo , Bin Chen , Sijie Yu

Flux emergence is ubiquitous in the Sun's lower atmosphere, where the emerging magnetic flux can reconnect with the pre-existing magnetic field. We investigate plasmoid formation and the resulting multi-thermal emissions during…

Solar and Stellar Astrophysics · Physics 2025-08-18 Guanchong Cheng , Lei Ni , Robert Cameron , Hardi Peter , Yajie Chen , Jun Lin

On the Sun, Doppler shifts of bidirectional outflows from the magnetic-reconnection site have been found only in confined regions through spectroscopic observations. Without spatially resolved spectroscopic observations across an extended…

Solar and Stellar Astrophysics · Physics 2022-11-21 Huidong Hu , Ying D. Liu , Lakshmi Pradeep Chitta , Hardi Peter , Mingde Ding

Magnetic reconnection modulated by non-local disturbances in the solar atmosphere has been investigated theoretically, but rarely observed. In this study, employing Ha and extreme ultraviolet (EUV) images and line of sight magnetograms, we…

Solar and Stellar Astrophysics · Physics 2021-03-10 Leping Li , Hardi Peter , Lakshmi Pradeep Chitta , Hongqiang Song , Kaifan Ji , Yongyuan Xiang

The first self-consistent simulations of electron acceleration during magnetic reconnection in a macroscale system are presented. Consistent with solar flare observations the spectra of energetic electrons take the form of power-laws that…

We propose a model of hard X-ray flares in protostars observed by ASCA satellite. Assuming that the dipole magnetic field of the protostar threads the protostellar disk, we carried out 2.5-dimensional magnetohydrodynamic (MHD) simulations…

Astrophysics · Physics 2009-10-28 M. R. Hayashi , K. Shibata , R. Matsumoto

Particle acceleration is one of the most significant features that are ubiquitous among space and cosmic plasmas. It is most prominent during flares in the case of the Sun, with which huge amount of electromagnetic radiation and high-energy…

Solar and Stellar Astrophysics · Physics 2014-05-15 Noriyuki Narukage , Masumi Shimojo , Taro Sakao

UV bursts and Ellerman bombs are transient brightenings observed in the low solar atmospheres of emerging flux regions. Observations have discovered the cospatial and cotemporal EBs and UV bursts, and their formation mechanisms are still…

Solar and Stellar Astrophysics · Physics 2021-02-17 Lei Ni , Yajie Chen , Hardi Peter , Hui Tian , Jun Lin

Microflares are small activities in solar low atmosphere, some are in the low corona, and others in the chromosphere. Observations show that some of the microflares are triggered by magnetic reconnection between emerging flux and a…

Solar and Stellar Astrophysics · Physics 2015-06-04 R. -L. Jiang , C. Fang , P. -F. Chen

We have recently developed the capability to make solar vector (Stokes IQUV) magnetograms using the infrared line of MgI at 12.32 microns. On 24 April 2001, we obtained a vector magnetic map of solar active region NOAA 9433, fortuitously…

Astrophysics · Physics 2009-11-07 Donald E. Jennings , Drake Deming , George McCabe , Pedro Sada , Thomas Moran

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…

Solar flares are known to be prolific electron accelerators, yet identifying the mechanism(s) for such efficient electron acceleration in solar flare (and similar astrophysical settings) presents a major challenge. This is due in part to a…

Solar and Stellar Astrophysics · Physics 2023-04-18 Eduard P. Kontar , A. Gordon Emslie , Galina G. Motorina , Brian R. Dennis