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Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close to the coronal Alfv\'{e}n speed. Yet, spectroscopic…

Solar and Stellar Astrophysics · Physics 2014-12-02 Hui Tian , Gang Li , Katharine K. Reeves , John C. Raymond , Fan Guo , Wei Liu , Bin Chen , Nicholas A. Murphy

We present the study of SOL2015-03-15 M1.2 flare, revealing acceleration of electrons and plasma heating in the sheared twisted magnetic structure in the polarity inversion line (PIL). The scope is to make the analysis of nonthermal…

Solar and Stellar Astrophysics · Physics 2018-09-19 I. N. Sharykin , I. V. Zimovets , I. I. Myshyakov , N. S. Meshalkina

We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, red-shifted…

Solar and Stellar Astrophysics · Physics 2023-06-29 Dong Li , Chuan Li , Ye Qiu , Shihao Rao , Alexander Warmuth , Frederic Schuller , Haisheng Zhao , Fanpeng Shi , Jun Xu , Zongjun Ning

Observations reveal a correspondence between chromospheric type II spicules and bright upwardly moving fronts in the corona observed in the EUV band. However, theoretical considerations suggest that these flows are unlikely to be the main…

Solar and Stellar Astrophysics · Physics 2014-09-05 A. Petralia , F. Reale , S. Orlando , J. A. Klimchuk

The energy released during solar flares is believed to be stored in non-potential magnetic fields associated with electric currents flowing in the corona. While no measurements of coronal electric currents are presently available, maps of…

Solar and Stellar Astrophysics · Physics 2015-08-19 Sophie Musset , Nicole Vilmer , Véronique Bommier

We present observations of the active M-dwarf binary AT Mic (dM4.5e+dM4.5e) obtained with the orbital observatory AstroSat. During 20 ks of observations, in the far ultraviolet ($130-180$ nm) and soft X-ray ($0.3-7$ keV) spectral ranges, we…

Solar and Stellar Astrophysics · Physics 2022-12-29 Alexey A. Kuznetsov , Ruslan R. Karakotov , Kalugodu Chandrashekhar , Dipankar Banerjee

In this paper, we present the results of an analysis of 481 weak solar flares, from A0.01 to the B \textit{GOES} class, that were observed during the period of extremely low solar activity from 2009 April to July. For all flares we measured…

Solar and Stellar Astrophysics · Physics 2017-06-20 A. S. Kirichenko , S. A. Bogachev

High resolution spectra from the Hinode EUV Imaging Spectrometer (EIS) have revealed that coronal spectral line profiles are sometimes asymmetric, with a faint enhancement in the blue wing on the order of 100 km/s. These asymmetries could…

Solar and Stellar Astrophysics · Physics 2015-06-11 David H. Brooks , Harry P. Warren

Context: One of the most prominent processes suggested to heat the corona to well above 10^6 K builds on nanoflares, short bursts of energy dissipation. Aims: We compare observations to model predictions to test the validity of the…

Solar and Stellar Astrophysics · Physics 2015-11-04 Leping Li , Hardi Peter , Feng Chen , Jun Zhang

We analyze a confined multiple-ribbon M2.1 flare (SOL2015-01-29T11:42) that originated from a fan-spine coronal magnetic field configuration, within active region NOAA 12268. The observed ribbons form in two steps. First, two primary…

Solar and Stellar Astrophysics · Physics 2017-10-11 Aaron Hernandez-Perez , Julia K. Thalmann , Astrid M. Veronig , Yang Su , Peter Gömöry , Ewan C. Dickson

The model of stochastic acceleration of particles by turbulence has been successful in explaining many observed features of solar flares. Here we demonstrate a new method to obtain the accelerated electron spectrum and important…

Solar and Stellar Astrophysics · Physics 2015-05-18 Vahe Petrosian , Qingrong Chen

Following a CME which started on 2002 November 26, RHESSI, the Ramaty High Energy Solar Spectroscopic Imager, observed for 12 hours an X-ray source above the solar limb, at altitudes between 0.1 and 0.3 RS above the photosphere. The GOES…

Solar and Stellar Astrophysics · Physics 2015-06-03 Pascal Saint-Hilaire , Sam Krucker , Robert P. Lin

Stellar flares affect all atmospheric layers from the photosphere over chromosphere and transition region up into the corona. Simultaneous observations in different spectral bands allow to obtain a comprehensive picture of the environmental…

Solar and Stellar Astrophysics · Physics 2015-05-18 Carolin Liefke , Birgit Fuhrmeister , Juergen H. M. M. Schmitt

We present the analyses of intense X-ray flares detected on the active fast rotator AB Dor using observations from the XMM-Newton. A total of 21 flares are detected, and 13 flares are analysed in detail. The total X-ray energy of these…

Solar and Stellar Astrophysics · Physics 2023-10-23 Shweta Didel , Jeewan C. Pandey , A. K. Srivastava , Gurpreet Singh

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

Heating signatures from small-scale magnetic reconnection events in the solar atmosphere have proven to be difficult to detect through observations. Numerical models that reproduce flaring conditions are essential in the understanding of…

Solar and Stellar Astrophysics · Physics 2022-03-30 H. Bakke , M. Carlsson , L. Rouppe van der Voort , B. V. Gudiksen , V. Polito , P. Testa , B. De Pontieu

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

We analyze the spectra of high temperature \fexxiv~lines observed by \emph{Hinode}/EIS during the impulsive phase of the X8.3--class flare on September 10, 2017. The line profiles are broad, show pronounced wings, and clearly depart from a…

Solar and Stellar Astrophysics · Physics 2018-09-05 Vanessa Polito , Jaroslav Dudík , Jana Kašparová , Elena Dzifčáková , Katharine K. Reeves , Paola Testa , Bin Chen

In this Letter, we present Interface Region Imaging Spectrograph Fe XXI 1354.08 A forbidden line emission of two magnetic flux ropes (MFRs) that caused two fast coronal mass ejections with velocities of $\ge$1000 km s$^{-1}$ and strong…

Solar and Stellar Astrophysics · Physics 2016-05-25 X. Cheng , M. D. Ding

We study the dynamics of low-lying cool loop systems for three datasets as observed by the Interface Region Imaging Spectrograph (IRIS). Radiances, Doppler shifts and line widths are investigated in and around observed cool loop systems…

Solar and Stellar Astrophysics · Physics 2019-03-27 Yamini K. Rao , Abhishek K. Srivastava , Pradeep Kayshap , Klaus Wilhelm , Bhola N. Dwivedi