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Theory of The Oblique Pulsator Model For The Rapidly Oscillating Ap Stars

Published online by Cambridge University Press:  12 April 2016

Hiromoto Shibahashi  and
Masao Takata
Hiromoto Shibahashi
Affiliation:
Department of Astronomy, University Of Tokyo, Tokyo 113, Japan
Masao Takata
Affiliation:
Department of Astronomy, University Of Tokyo, Tokyo 113, Japan

Abstract

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Recently, one of the rapidly oscillating Ap stars, HR 3831, has been found to have an equally split frequency septuplet, though its oscillation seems to be essentially an axisymmetric dipole mode with respect to the magnetic axis which is oblique to the rotation axis (Kurtz et al. 1992; Kurtz 1992). In order to explain this fine structure, we investigate oscillations of rotating magnetic stars by taking account of the perturbations due to the magnetic fields and the rotation. We show that the magnetic field on axisymmetric dipole modes distorts the dipole oscillation pattern to have axisymmetric octapole components so that the frequency pattern becomes a septuplet rather than a triplet, and that the additional effect of the rotation leads the frequency pattern to be asymmetric. The formula allows us to get information about the magnetic fields, the rotation, and the geometrical configuration of the star from the oscillation data.

Type
VI. Asteroseismology: theory
Information
International Astronomical Union Colloquium , Volume 137: Inside the Stars , 1993 , pp. 563 - 565
Copyright
Copyright © Astronomical Society of the Pacific 1993

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