Impulsive heating of solar flare ribbons above 10 MK

Simoes, P. J.A. , Graham, D. R. and Fletcher, L. (2015) Impulsive heating of solar flare ribbons above 10 MK. Solar Physics, 290(12), pp. 3573-3591. (doi:10.1007/s11207-015-0709-9)

Simoes, P. J.A. , Graham, D. R. and Fletcher, L. (2015) Impulsive heating of solar flare ribbons above 10 MK. Solar Physics, 290(12), pp. 3573-3591. (doi:10.1007/s11207-015-0709-9)

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Abstract

The chromospheric response to the input of flare energy is marked by extended extreme ultraviolet (EUV) ribbons and hard X-ray (HXR) footpoints. These are usually explained as the result of heating and bremsstrahlung emission from accelerated electrons colliding in the dense chromospheric plasma. We present evidence of impulsive heating of flare ribbons above 10 MK in a two-ribbon flare. We analyse the impulsive phase of SOL2013-11-09T06:38, a C2.6 class event using data from Atmospheric Imaging Assembly (AIA) on board of Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to derive the temperature, emission measure and differential emission measure of the flaring regions and investigate the evolution of the plasma in the flaring ribbons. The ribbons were visible at all SDO/AIA EUV/UV wavelengths, in particular, at 94 and 131 \AA\ filters, sensitive to temperatures of 8 MK and 12 MK. Time evolution of the emission measure of the plasma above 10 MK at the ribbons has a peak near the HXR peak time. The presence of hot plasma in the lower atmosphere is further confirmed by RHESSI imaging spectroscopy analysis, which shows resolved sources at 11-13 MK associated with at least one ribbon. We found that collisional beam heating can only marginally explain the necessary power to heat the 10 MK plasma at the ribbons.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Graham, Mr David and Simoes, Dr Paulo and Fletcher, Professor Lyndsay
Authors: Simoes, P. J.A., Graham, D. R., and Fletcher, L.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Solar Physics
Publisher:Springer Verlag
ISSN:0038-0938
ISSN (Online):1573-093X
Copyright Holders:Copyright © 2015 Springer Science+Business Media Dordrecht
First Published:First published in Solar Physics 290(12):3573-3591
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
595181Chromospheric Flares: Observations, Models and Archives (CHROMA)Lyndsay FletcherEuropean Commission (EC)606862P&A - PHYSICS & ASTRONOMY
542081Rolling Programme in Solar and Plasma AstrophysicsLyndsay FletcherScience & Technologies Facilities Council (STFC)ST/I001808/1P&A - PHYSICS & ASTRONOMY