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Theory of Amplitude Modulation II. The Resonant Mode Interaction Model

Published online by Cambridge University Press:  12 April 2016

Tim Van Hoolst*
Affiliation:
Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, BelgiumInstitute of Astronomy, Katholieke Universiteit Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium

Abstract

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With about one fourth of the RRab stars showing the Blazhko effect, amplitude modulation on long time scales is a common phenomenon in stellar pulsation. The role of nonradial oscillation modes is studied here, and it is proposed that the amplitude modulation is a result of a dynamical, nonlinear resonance between the observed radial mode and a low-degree nonradial mode. In this scenario, a nonradial mode is resonantly excited in Blazhko-type RR Lyrae stars. Degree one modes are found to have the highest probability of being excited and a crucial test of the model would be the observational determination of the degree of the proposed nonradial mode.

Type
Part 4. Blazhko Phenomenon
Copyright
Copyright © Astronomical Society of the Pacific 2000

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