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An “A star” on an M star during a flare within a flare

Published online by Cambridge University Press:  26 August 2011

Adam F. Kowalski ,
Suzanne L. Hawley ,
Jon A. Holtzman ,
John P. Wisniewski  and
Eric J. Hilton
Adam F. Kowalski
Affiliation:
Astronomy Department, University of Washington Box 351580, Seattle, WA 98195, USA email: kowalski@astro.washington.edu
Suzanne L. Hawley
Affiliation:
Astronomy Department, University of Washington Box 351580, Seattle, WA 98195, USA email: kowalski@astro.washington.edu
Jon A. Holtzman
Affiliation:
Department of Astronomy, New Mexico State University Box 30001, Las Cruces, NM 88003, USA
John P. Wisniewski
Affiliation:
Astronomy Department, University of Washington Box 351580, Seattle, WA 98195, USA email: kowalski@astro.washington.edu NSF Astronomy & Astrophysics Postdoctoral Fellow
Eric J. Hilton
Affiliation:
Astronomy Department, University of Washington Box 351580, Seattle, WA 98195, USA email: kowalski@astro.washington.edu
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Abstract

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M dwarfs produce explosive flare emission in the near-UV and optical continuum, and the mechanism responsible for this phenomenon is not well-understood. We present a near-UV/optical flare spectrum from the rise phase of a secondary flare, which occurred during the decay of a much larger flare. The newly formed flare emission resembles the spectrum of an early-type star, with the Balmer lines and continuum in absorption. We model this observation phenomenologically as a temperature bump (hot spot) near the photosphere of the M dwarf. The amount of heating implied by our model (ΔTphot ~ 16,000 K) is far more than predicted by chromospheric backwarming in current 1D RHD flare models (ΔTphot ~ 1200 K).

Keywords

Physical data and processes: radiative transferastronomical methods: numericalatmospheric effectstechniques: spectroscopicstars: atmospheresstars: flarestars: late-type
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 261 - 264
Copyright
Copyright © International Astronomical Union 2011

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