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The Oblique Pulsator Model for the Blazhko Effect in RR Lyrae Stars. Theory of Amplitude Modulation I

Published online by Cambridge University Press:  12 April 2016

Hiromoto Shibahashi
Hiromoto Shibahashi*
Affiliation:
Department of Astronomy, University of Tokyo, Tokyo 113-0033, Japan

Abstract

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By assuming that RR Lyrae stars have fairly strong dipole magnetic fields with symmetry axis oblique to the rotation axis of the star, I show that the oscillation mode which would be a pure radial oscillation in absence of the magnetic field has a quadrupole component, whose symmetry axis coincides with the magnetic axis. The aspect angle of the quadrupole component changes due to the stellar rotation, and this apparent amplitude variation is interpreted as the Blazhko effect in RR Lyrae stars. It is shown that, in the case of off-axis magnetic field, phase modulation is expected. I list up some theoretical predictions based on this model, which would observationally examine this hypothesis.

Type
Part 4. Blazhko Phenomenon
Information
International Astronomical Union Colloquium , Volume 176: The Impact of Large-Scale Surveys on Pulsating Star Research , 2000 , pp. 299 - 306
Copyright
Copyright © Astronomical Society of the Pacific 2000

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