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An Observationally Constrained Model of a Flux Rope that Formed in the Solar Corona

James, AW; Valori, G; Green, LM; Liu, Y; Cheung, MCM; Guo, Y; van Driel-Gesztelyi, L; (2018) An Observationally Constrained Model of a Flux Rope that Formed in the Solar Corona. The Astrophysical Journal Letters , 855 (2) , Article L16. 10.3847/2041-8213/aab15d. Green open access

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Abstract

Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the coronae of stars. Understanding the plasma processes involved in CME initiation has applications for space weather forecasting and laboratory plasma experiments. James et al. used extreme-ultraviolet (EUV) observations to conclude that a magnetic flux rope formed in the solar corona above NOAA Active Region 11504 before it erupted on 2012 June 14 (SOL2012-06-14). In this work, we use data from the Solar Dynamics Observatory (SDO) to model the coronal magnetic field of the active region one hour prior to eruption using a nonlinear force-free field extrapolation, and find a flux rope reaching a maximum height of 150 Mm above the photosphere. Estimations of the average twist of the strongly asymmetric extrapolated flux rope are between 1.35 and 1.88 turns, depending on the choice of axis, although the erupting structure was not observed to kink. The decay index near the apex of the axis of the extrapolated flux rope is comparable to typical critical values required for the onset of the torus instability, so we suggest that the torus instability drove the eruption.

Type: Article
Title: An Observationally Constrained Model of a Flux Rope that Formed in the Solar Corona
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/2041-8213/aab15d
Publisher version: http://doi.org/10.3847/2041-8213/aab15d
Language: English
Additional information: Copyright © 2018. The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords: Sun: corona, Sun: coronal mass ejections (CMEs), Sun: magnetic fields
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/10046199
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