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| Paper: |
Magnetic Perturbations to Stellar rho-mode Frequencies |
| Volume: |
135, A Half Century of Stellar Pulsation Interpretations: a Tribute to Arthur N. Cox |
| Page: |
118 |
| Authors: |
Cunha, M. M. S. |
| Abstract: |
We study the effect of a magnetic field on the frequencies of stellar acoustic modes with various degrees l and azimuthal orders m,in the case when the field cuts the surface of the star, preventing the use of nonsingular perturbation theory. Special attention is given to the use of a variational principle in order to determine the shifts in the frequencies, while avoiding having to calculate the perturbed eigenfunctions. The method allows one to construct a Green function permitting one to calculate the frequency perturbation of any mode of moderate or low degree by an arbitrary magnetic field. The loss of energy through the Alfven waves propagating into the star is also estimated through the imaginary part of the frequency shift. The results indicate that, for magnetic fields believed to be typical of roAp stars, the frequency shifts are of the order of few 5Hz. |
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