Pulsations of rapidly rotating stars with compositional discontinuities

Abstract

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.

4 pages, 4 figures, proceedings of the IAU Symposium 301, Precision Asteroseismology, August 2013, Wroclaw, Poland

References in corpus (5)

• Acoustic oscillations in rapidly rotating polytropic stars I. Effects of the centrifugal distortion
• Relationship between low and high frequencies in Delta Scuti stars: Photometric Kepler and spectroscopic analyses of the rapid rotator KIC 8054146
• Regular Oscillation Sub-spectrum of Rapidly Rotating Stars
• Ab initio modelling of steady rotating stars
• Detection of high-degree prograde sectoral mode sequences in the A-star KIC 8054146?

Cited by in corpus (2)

• Theoretical power spectra of mixed modes in low mass red giant stars
• Oscillations of 2D ESTER models. I. The adiabatic case