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Even small solar flares can display a surprising level of complexity regarding their morphology and temporal evolution. Many of their properties, such as energy release and electron acceleration can be studied using highly complementary…

Solar and Stellar Astrophysics · Physics 2021-12-08 Marina Battaglia , Rohit Sharma , Yingjie Luo , Bin Chen , Sijie Yu , Säm Krucker

In the standard model, magnetic reconnection at a vertical current sheet above the flare arcade is key to explaining many aspects of solar eruptions. The supra-arcade region is where the vertical current sheet is supposedly located, and…

Solar and Stellar Astrophysics · Physics 2025-12-23 Hanya Pan , Astrid M. Veronig , Rui Liu

We present observations of an eruptive solar flare on 2016 January 6 that occurred behind the solar limb from the perspective of the Earth, but was well observed by STEREO and the Solar Extreme Ultraviolet Monitor on the Mars Atmosphere and…

We studied the developing conditions of sigmoid structure under the influence of magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from Helioseismic Magnetic…

Solar and Stellar Astrophysics · Physics 2016-09-28 P. Vemareddy , X. Cheng , B. Ravindra

We investigate the evolution of NOAA Active Region 11817 during 2013 August 10--12, when it developed a complex field configuration and produced four confined, followed by two eruptive, flares. These C-and-above flares are all associated…

Solar and Stellar Astrophysics · Physics 2016-02-22 Rui Liu , Bernhard Kliem , Viacheslav S. Titov , Jun Chen , Yuming Wang , Haimin Wang , Chang Liu , Yan Xu , Thomas Wiegelmann

We analyse the multiwavelength observations of an M2.9/1N flare that occurred in the active region (AR) NOAA 11112 in the vicinity of a huge filament system on 16 October 2010. SDO/HMI magnetograms reveal the emergence of a bipole (within…

Solar and Stellar Astrophysics · Physics 2015-06-11 Pankaj Kumar , Sung-Hong Park , K. -S. Cho , S. -C. Bong

Nonthermal electrons accelerated in solar flares produce electromagnetic emission in two distinct, highly complementary domains - hard X-rays (HXRs) and microwaves (MWs). This paper reports MW imaging spectroscopy observations from the…

Solar and Stellar Astrophysics · Physics 2020-04-29 Natsuha Kuroda , Gregory D. Fleishman , Dale E. Gary , Gelu M. Nita , Bin Chen , Sijie Yu

We study a solar flare that occurred on September 10, 2002, in active region NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the radio range. The event was classified as M2.9 in X-rays and 1N in H\alpha. Solar…

Solar and Stellar Astrophysics · Physics 2015-06-11 C. G. Giménez de Castro , G. D. Cristiani , P. J. A. Simões , C. H. Mandrini , E. Correia , P. Kaufmann

Strong solar flares and coronal mass ejections, here defined not only as the bursts of electromagnetic radiation but as the entire process in which magnetic energy is released through magnetic reconnection and plasma instability, emanate…

Solar and Stellar Astrophysics · Physics 2019-05-29 Shin Toriumi , Haimin Wang

Homologous flares are flares that occur repetitively in the same active region, with similar structure and morphology. A series of at least eight homologous flares occurred in active region NOAA 11237 over 16 - 17 June 2011. A nearby…

Solar and Stellar Astrophysics · Physics 2015-09-23 Navdeep K. Panesar , Alphonse C. Sterling , Davina E. Innes , Ronald L. Moore

We present observations of a confined M4.0 flare from NOAA 11302 on 2011 September 26. Observations at high temporal, spatial, and spectral resolution from Solar Dynamics Observatory, Reuven Ramaty High Energy Solar Spectroscopic Imager,…

Solar and Stellar Astrophysics · Physics 2014-08-05 Upendra Kushwaha , Bhuwan Joshi , Kyung-Suk Cho , Astrid Veronig , Sanjiv Kumar Tiwari , S. K. Mathew

During eruptive flares, vector magnetograms show increasing horizontal magnetic field and downward Lorentz force in the Sun's photosphere around the polarity-inversion line. Such behavior has often been associated with the implosion…

Solar and Stellar Astrophysics · Physics 2019-06-05 Krzysztof Barczynski , Guillaume Aulanier , Sophie Masson , Michael S. Wheatland

We investigate the relationship between the continuum enhancement and the hard X-ray (HXR) emission of a white-light flare on 2002 September 29. By reconstructing the RHESSI HXR images in the impulsive phase, we find two bright conjugate…

Astrophysics · Physics 2014-10-13 Q. R. Chen , M. D. Ding

During the rising phase of Solar Cycle 24 tremendous activity occurred on the Sun with fast and compact emergence of magnetic flux leading to bursts of flares (C to M and even X-class). We investigate the violent events occurring in the…

Solar and Stellar Astrophysics · Physics 2015-06-18 C. H. Mandrini , B. Schmieder , P. Démoulin , Y. Guo , G. D. Cristiani

A current sheet, where magnetic energy is liberated through reconnection and is converted to other forms, is thought to play the central role in solar flares, the most intense explosions in the heliosphere. However, the evolution of a…

Solar and Stellar Astrophysics · Physics 2021-04-28 L. P. Chitta , E. R. Priest , X. Cheng

Using multi-wavelength data of Hinode, a rapid rotation of a sunspot in active region NOAA 10930 is studied in detail. We found the extra-ordinary counterclockwise rotation of the sunspot with positive polarity before an X3.4 flare. From a…

Solar and Stellar Astrophysics · Physics 2009-11-13 Xiaoli Yan

We analyze the temporal evolution of the three-dimensional (3D) magnetic structure of the flaring active region (AR) NOAA 10930 by using the nonlinear force-free fields extrapolated from the photospheric vector magnetic fields observed by…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. Inoue , D. Shiota , T. T. Yamamoto , V. S. Pandey , T. Magara , G. S. Choe

To better understand magnetic structure and eruptive process of solar filaments, a solar active-region filament (labeled F2) eruption associated with a B-class flare was investigated by using high-resolution H$\alpha$ data from the 1 m New…

Solar and Stellar Astrophysics · Physics 2020-11-25 X. L. Yan , Q. L. Li , G. R. Chen , Z. K. Xue , L. Feng , J. C. Wang , L. H. Yang , Y. Zhang

Solar flares may be the best-known examples of the explosive conversion of magnetic energy into bulk motion, plasma heating, and particle acceleration via magnetic reconnection. The energy source for all flares is the highly sheared…

Solar and Stellar Astrophysics · Physics 2022-08-02 Joel T. Dahlin , Spiro K. Antiochos , Jiong Qiu , C. Richard DeVore

We investigated four major solar flare events that occurred in active regions NOAA 10930 (December 13 and 14, 2006) and NOAA 11158 (February 13 and 15, 2011) by using data observed by the Solar Optical Telescope (SOT) onboard the Hinode…

Solar and Stellar Astrophysics · Physics 2015-06-17 Y. Bamba , K. Kusano , T. T. Yamamoto , T. J. Okamoto