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Radial pulsation stability as a function of hydrogen abundance

Published online by Cambridge University Press:  27 October 2016

C.S. Jeffery  and
H. Saio
C.S. Jeffery
Affiliation:
Armagh Observatory, College Hill, Armagh BT61 9DG, UK
H. Saio
Affiliation:
Astronomical Institute, School of Science, Tohoku University, Sendai 980-8578, Japan
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Abstract

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We explore the radial (p-mode) stability of stars across a wide range of mass (0.2 < M < 50 M⊙), composition (0 < X < 0.7, Z = 0.001, 0.02), effective temperature, and luminosity. We identify the instability boundaries associated with low- to high-order radial oscillations (0 ⩽ n ⩽ 13). The instability boundaries are a strong function of both composition and radial order (n). The classical blue edge shifts to higher effective temperature and luminosity with decreasing hydrogen abundance. High-order modes are more easily excited and small islands of high radial-order instability develop, some of which correspond with real stars. Driving in all cases is by the classical κ-mechanism and, at high luminosity-to-mass ratio, strange-mode instability. We identify regions of parameter space where new classes of pulsating variable have recently or may, in future, be discovered. The majority of these are associated with reduced hydrogen abundance in the envelope.

Keywords

stars: oscillationsstars: interiorsstars: white-dwarfstars: subdwarfsstars: early-type
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , General Assembly A29B: Astronomy in Focus , August 2015 , pp. 548 - 551
Copyright
Copyright © International Astronomical Union 2016 

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