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Serial Flaring in an Active Region: Exploring Why Only One Flare Is Eruptive

Woods, MM; Inoue, S; Harra, LK; Matthews, SA; Kusano, K; (2020) Serial Flaring in an Active Region: Exploring Why Only One Flare Is Eruptive. The Astrophysical Journal , 890 (1) , Article 84. 10.3847/1538-4357/ab6bc8. Green open access

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Abstract

Over a four hour period between 2014 June 12–13 a series of three flares were observed within AR 12087. This sequence of flares started with a non-eruptive M-class flare, followed by a non-eruptive C-class flare, and finally ended with a second C-class flare that had an associated filament eruption. In this paper we combine spectroscopic analysis of Interface Region Imaging Spectrometer observations of the Si iv line during the three flares along with a series of nonlinear force-free field (NLFFF) extrapolations in order to investigate the conditions that lead the final flare to be eruptive. From this analysis it is found to be unlikely that the eruption was triggered by either kink instability or by tether-cutting reconnection, allowing the flux rope to rise into a region where it would be susceptible to the torus instability. The NLFFF modeling does, however, suggest that the overlying magnetic field has a fan-spine topology, raising the possibility that breakout reconnection occurring during the first two flares weakened the overlying field, allowing the flux rope to erupt in the subsequent third flare.

Type: Article
Title: Serial Flaring in an Active Region: Exploring Why Only One Flare Is Eruptive
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/ab6bc8
Publisher version: https://doi.org/10.3847/1538-4357/ab6bc8
Language: English
Additional information: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (http://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords: Solar flare spectra; Solar physics; Solar active regions; Solar activity; Solar active region magnetic fields; Solar active region filaments; Solar flares
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10091691
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