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Pulsations of rapidly rotating stars with compositional discontinuities

Published online by Cambridge University Press:  18 February 2014

Daniel R. Reese ,
Francisco Espinosa Lara  and
Michel Rieutord
Daniel R. Reese
Affiliation:
Institut d'Astrophysique et Géophysique de l'Université de Liège, Allée du 6 Août 17, 4000 Liège, Belgium email: [email protected]
Francisco Espinosa Lara
Affiliation:
Universté de Toulouse, UPS-OMP, IRAP, Toulouse, France CNRS, IRAP, 14 avenue Edouard Belin, 31400 Toulouse, France
Michel Rieutord
Affiliation:
Universté de Toulouse, UPS-OMP, IRAP, Toulouse, France CNRS, IRAP, 14 avenue Edouard Belin, 31400 Toulouse, France
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Abstract

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Recent observations of rapidly rotating stars have revealed the presence of regular patterns in their pulsation spectra. This has raised the question as to their physical origin, and, in particular, whether they can be explained by an asymptotic frequency formula for low-degree acoustic modes, as recently discovered through numerical calculations and theoretical considerations. In this context, a key question is whether compositional/density gradients can adversely affect such patterns to the point of hindering their identification. To answer this question, we calculate frequency spectra using two-dimensional ESTER stellar models. These models use a multi-domain spectral approach, allowing us to easily insert a compositional discontinuity while retaining a high numerical accuracy. We analyse the effects of such discontinuities on both the frequencies and eigenfunctions of pulsation modes in the asymptotic regime. We find that although there is more scatter around the asymptotic frequency formula, the semi-large frequency separation can still be clearly identified in a spectrum of low-degree acoustic modes.

Keywords

stars: oscillationsstars: rotationstars: interiors
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 9 , Symposium S301: Precision Asteroseismology , August 2013 , pp. 169 - 172
Copyright
Copyright © International Astronomical Union 2014 

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