| Issue |
A&A
Volume 398, Number 2, February I 2003
|
|
|---|---|---|
| Page(s) | 663 - 675 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:20021671 | |
| Published online | 21 January 2003 | |
Oscillations of magnetic stars: I. Axisymmetric shear Alfvén modes of a spherical shell in a dipolar magnetic field
1
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, rincon@ast.obs-mip.fr
Received:
15
May
2002
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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