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Astron. Astrophys. 338, L55-L58 (1998)

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Letter to the Editor

Simulations of an alpha-effect due to magnetic buoyancy

Axel Brandenburg 1 and Dieter Schmitt 2

1 Department of Mathematics, University of Newcastle upon Tyne, NE1 7RU, UK
2 Universitäts-Sternwarte Göttingen, Geismarlandstrasse 11, D-37083 Göttingen, Germany

Received 20 July 1998 / Accepted 20 August 1998

Abstract

Three-dimensional simulations of a thermally stably stratified gas with a localized layer of toroidal magnetic field are carried out. The magnetic field gives rise to a magnetic buoyancy instability. Due to the presence of rotation the resulting fluid motions are helical and lead to an [FORMULA]-effect, i.e. to a component of the electromotive force in the direction of the mean magnetic field. The value of [FORMULA] is estimated during the exponential growth phase of the instability. The mean vertical transport velocity of the magnetic field is also calculated. It is found that [FORMULA] varies with latitude and its value is positive in the northern hemisphere.

Key words: Sun: magnetic fields – magnetohydrodynamics – dynamo – instabilities

This article contains no SIMBAD objects.

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© European Southern Observatory (ESO) 1998

Online publication: September 14, 1998
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