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Astron. Astrophys. 343, 977-982 (1999)

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The Maunder minimum as due to magnetic [FORMULA]-quenching

M. Küker, R. Arlt and G. Rüdiger

Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany

Received 7 September 1998 / Accepted 7 December 1998


We study the nonlinear interplay between dynamo-induced magnetic fields and differential rotation in stellar convection zones. The magnetic back reaction is threefold: Lorentz force, [FORMULA]-quenching and [FORMULA]-quenching. If only the Malkus-Proctor feedback is used, the dynamo shows an interesting non-periodic behavior which, however, disappears when [FORMULA] quenching is included (cf. Fig. 2). If also a strong [FORMULA]-quenching is allowed to modify the differential rotation, the dynamo resumes its exotic performance with periodically changing cycle periods and fluctuating magnetic parities. The Elsasser number has been set to unity whereas the magnetic Prandtl number must be smaller than unity. For too small magnetic Prandtl numbers (e.g. for [FORMULA]), however, the grand minima seldom occur.

Key words: Magnetohydrodynamics (MHD) – turbulence – Sun: activity – Sun: rotation – stars: late-type – stars: magnetic fields

Send offprint requests to: G. Rüdiger

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999