Volume 398, Number 2, February I 2003
|Page(s)||663 - 675|
|Section||Stellar structure and evolution|
|Published online||21 January 2003|
Oscillations of magnetic stars: I. Axisymmetric shear Alfvén modes of a spherical shell in a dipolar magnetic field
Laboratoire d'Astrophysique de Toulouse, Observatoire Midi-Pyrénées, 14 avenue É. Belin, 31400 Toulouse, France
2 École Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France
3 Institut Universitaire de France
Corresponding author: F. Rincon, email@example.com
Accepted: 5 November 2002
We carry out an investigation of axisymmetric shear Alfvén waves in a spherical layer of an incompressible resistive fluid when a strong dipolar magnetic field is applied. A decomposition on the spherical harmonics base is used to compute the eigenmodes of the system. Numerical results show that the least-damped Alfvénic modes naturally concentrate near the magnetic polar axis. These modes also show internal shear/magnetic layers associated with resonant field lines. This model is useful when modelling planetary cores sustaining a dynamo, magnetic neutron stars or to the magnetic layer of roAp stars. In this latter case, it shows that shear Alfvén waves provide a good instance of non-perturbative effects due to the strong magnetic field of such stars.
Key words: MHD / stars: oscillations / stars: magnetic fields / stars: chemically peculiar
© ESO, 2003
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