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

Journal Article · Wed Oct 01 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/793/2/70· OSTI ID:22370594

Milligan, Ryan O.; Mathioudakis, Mihalis; Keenan, Francis P. ^[1]; Kerr, Graham S.; Hudson, Hugh S.; Fletcher, Lyndsay ^[2]; Dennis, Brian R.; Allred, Joel C.; Chamberlin, Phillip C.; Ireland, Jack ^[3]

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1. Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN (United Kingdom)
2. School of Physics and Astronomy, SUPA, University of Glasgow, Glasgow G12 8QQ (United Kingdom)
3. Solar Physics Laboratory (Code 671), Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

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 × 10{sup 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 Å and H I (Lyα) at 1216 Å by SDO/EVE, the UV continua at 1600 Å and 1700 Å by SDO/AIA, and the white light continuum at 4504 Å, 5550 Å, and 6684 Å, along with the Ca II H line at 3968 Å using Hinode/SOT. The summed energy detected by these instruments amounted to ∼3 × 10{sup 30} erg; about 15% of the total nonthermal energy. The Lyα 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 modeling 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.

• OSTI ID: 22370594
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 793; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CHROMOSPHERE
DISTRIBUTION
ELECTRONS
EMISSION
ENERGY BALANCE
EVOLUTION
EXTREME ULTRAVIOLET RADIATION
GAMMA RADIATION
HARD X RADIATION
INJECTION
LYMAN LINES
PLASMA
SOLAR FLARES
SUN
ULTRAVIOLET RADIATION
VISIBLE RADIATION
WAVELENGTHS