The radiated energy budget of chromospheric plasma in a major solar flare deduced from multi-wavelength observations

Milligan, R. O., Kerr, G. S.,, Dennis, B. R., Hudson, H. S. , Fletcher, L. , Allred, J. C., Chamberlin, P. C., Ireland, J., Mathioudakis, M. and Keenan, F. P. (2014) The radiated energy budget of chromospheric plasma in a major solar flare deduced from multi-wavelength observations. Astrophysical Journal, 793(2), p. 70. (doi:10.1088/0004-637X/793/2/70)

Milligan, R. O., Kerr, G. S.,, Dennis, B. R., Hudson, H. S. , Fletcher, L. , Allred, J. C., Chamberlin, P. C., Ireland, J., Mathioudakis, M. and Keenan, F. P. (2014) The radiated energy budget of chromospheric plasma in a major solar flare deduced from multi-wavelength observations. Astrophysical Journal, 793(2), p. 70. (doi:10.1088/0004-637X/793/2/70)

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Abstract

This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form of nonthermal electrons. Hard X-ray observations from RHESSI were used to track the evolution of the parameters of the nonthermal electron distribution to reveal the total power contained in flare accelerated electrons. By integrating over the duration of the impulsive phase, the total energy contained in the nonthermal electrons was found to be >2 x 10^{31} erg. The response of the lower solar atmosphere was measured in the free-bound EUV continua of H I (Lyman), He I, and He II, plus the emission lines of He II at 304 A and H I (Ly-alpha) at 1216 A by SDO/EVE, the UV continua at 1600 A and 1700 A by SDO/AIA, and the WL continuum at 4504 A, 5550 A, and 6684 A, along with the Ca II H line at 3968 A using Hinode/SOT. The summed energy detected by these instruments amounted to ~3 x 10^{30} erg; about 15% of the total nonthermal energy. The Ly-alpha line was found to dominate the measured radiative losses. Parameters of both the driving electron distribution and the resulting chromospheric response are presented in detail to encourage the numerical modelling of flare heating for this event, to determine the depth of the solar atmosphere at which these line and continuum processes originate, and the mechanism(s) responsible for their generation.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hudson, Dr Hugh and Kerr, Graham and Fletcher, Professor Lyndsay
Authors: Milligan, R. O., Kerr, G. S.,, Dennis, B. R., Hudson, H. S., Fletcher, L., Allred, J. C., Chamberlin, P. C., Ireland, J., Mathioudakis, M., and Keenan, F. P.
Subjects:Q Science > QB Astronomy
Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Group:Astronomy & Astrophysics
Journal Name:Astrophysical Journal
Publisher:Institute of Physics Publishing Ltd.
ISSN:0004-637X
ISSN (Online):1538-4357
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
542081Rolling Programme in Solar and Plasma AstrophysicsLyndsay FletcherScience & Technologies Facilities Council (STFC)ST/I001808/1P&A - PHYSICS & ASTRONOMY
595181Chromospheric Flares: Observations, Models and Archives (CHROMA)Lyndsay FletcherEuropean Commission (EC)606862P&A - PHYSICS & ASTRONOMY