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Nonlinear Dynamo Modes and Timescales of Stellar Activity

Published online by Cambridge University Press:  08 February 2017

G. Belvedere  and
M. R. E. Proctor
G. Belvedere
Affiliation:
(∗)Istituto di Astronomia, Università di Catania, Italy.
M. R. E. Proctor
Affiliation:
(∗∗)Dept. Applied Mathamtics and Theoretical Physics. University of Cambridge, UK.

Abstract

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A simple mean-field model of a nonlinear stellar α-ω dynamo is considered, in which dynamo action is supposed to occur in a spherical shell, and where the main nonlinearity retained is the influence of the Lorentz force on the zonal flow field. The equations are simplified by truncating in the radial direction, while full latitudinal dependence is retained. The resulting nonlinear p.d.e.'s in latitude and time are solved numerically, and it is found that while regular dynamo wave type solutions are stable when the dynamo number D is sufficiently close to its critical value, there is a wide variety of stable solutions at larger values of D. Furthermore, two different types of dynamo can coexist at the same parameter values. Implications for fields in late-type stars are discussed.

Type
VII. Convection and Magnetic Fields in Solar-type Stars
Information
Symposium - International Astronomical Union , Volume 138: Solar Photosphere: Structure, Convection and Magnetic Fields , 1990 , pp. 447 - 453
Copyright
Copyright © Kluwer 1990 

References

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