EDP Sciences
Free access
Issue A&A
Volume 452, Number 1, June II 2006
Page(s) 343 - 346
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20054608



A&A 452, 343-346 (2006)
DOI: 10.1051/0004-6361:20054608

Quasi-periodic modulation of solar and stellar flaring emission by magnetohydrodynamic oscillations in a nearby loop

V. M. Nakariakov, C. Foullon, E. Verwichte and N. P. Young

Physics Department, University of Warwick, Coventry, CV4 7AL, UK
    e-mail: V.Nakariakov@warwick.ac.uk

(Received 30 November 2005 / Accepted 20 February 2006)

Abstract
We propose a new model for quasi-periodic modulation of solar and stellar flaring emission. Fast magnetoacoustic oscillations of a non-flaring loop can interact with a nearby flaring active region. This interaction occurs when part of the oscillation situated outside the loop reaches the regions of steep gradients in magnetic field within an active region and produces periodic variations of electric current density. The modulation depth of these variations is a few orders of magnitude greater than the amplitude of the driving oscillation. The variations of the current can induce current-driven plasma micro-instabilities and thus anomalous resistivity. This can periodically trigger magnetic reconnection, and hence acceleration of charged particles, producing quasi-periodic pulsations of X-ray, optical and radio emission at the arcade footpoints.


Key words: Sun: flares -- Sun: oscillations -- Sun: corona -- stars: flare -- stars: oscillations -- stars: coronae




© ESO 2006

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Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: C. Bertout

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

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