EDP Sciences
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Volume 381, Number 3, January III 2002
Page(s) 923 - 932
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011465

A&A 381, 923-932 (2002)
DOI: 10.1051/0004-6361:20011465

Dynamo action by differential rotation in a stably stratified stellar interior

H. C. Spruit

Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching, Germany

(Received 13 August 2001 / Accepted 18 October 2001 )

Magnetic fields can be created in stably stratified (non-convective) layers in a differentially rotating star. A magnetic instability in the toroidal field (wound up by differential rotation) replaces the role of convection in closing the field amplification loop. Tayler instability is likely to be the most relevant magnetic instability. A dynamo model is developed from these ingredients, and applied to the problem of angular momentum transport in stellar interiors. It produces a predominantly horizontal field. This dynamo process is found to be more effective in transporting angular momentum than the known hydrodynamic mechanisms. It might account for the observed pattern of rotation in the solar core.

Key words: magnetohydrodynamics (MHD) -- stars: magnetic fields -- instabilities

© ESO 2002