Anfinogentov, S., Nakariakov, V. M. (Valery M.), Mathioudakis, M., Van Doorsselaere, T. and Kowalski, A. F. (2013) The decaying long-period oscillation of a stellar megaflare. The Astrophysical Journal, Volume 773 (Number 2). Article number 156. doi:10.1088/0004-637X/773/2/156

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Abstract

We analyze and interpret the oscillatory signal in the decay phase of the U-band light curve of a stellar megaflare observed on 2009 January 16 on the dM4.5e star YZ CMi. The oscillation is well approximated by an exponentially decaying harmonic function. The period of the oscillation is found to be 32 minutes, the decay time about 46 minutes, and the relative amplitude 15%. As this observational signature is typical of the longitudinal oscillations observed in solar flares at extreme ultraviolet and radio wavelengths, associated with standing slow magnetoacoustic waves, we suggest that this megaflare may be of a similar nature. In this scenario, macroscopic variations of the plasma parameters in the oscillations modulate the ejection of non-thermal electrons. The phase speed of the longitudinal (slow magnetoacoustic) waves in the flaring loop or arcade, the tube speed, of about 230 km s-1 would require a loop length of about 200 Mm. Other mechanisms, such as standing kink oscillations, are also considered.

Item Type:	Journal Article
Divisions:	Faculty of Science > Physics
Journal or Publication Title:	The Astrophysical Journal
Publisher:	Institute of Physics Publishing, Inc.
ISSN:	0004-637X
Official Date:	August 2013
Dates:	Date Event August 2013 Published
Volume:	Volume 773
Number:	Number 2
Number of Pages:	5
Article Number:	Article number 156
DOI:	10.1088/0004-637X/773/2/156
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access

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