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High- and Low-Degree Modes in Delta Scuti Stars: 1- and 2-D Fourier Analyses Of τ Peg

Published online by Cambridge University Press:  12 April 2016

Edward J. Kennelly
Affiliation:
Department of Geophysics & Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1W5Canada
Jaymie M. Matthews
Affiliation:
Department of Geophysics & Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1W5Canada Departement de physique, Université de Montreal, C.P. 6128, succ. A, Montréal, Québec H3C 3J7Canada
Gordon A.H. Walker
Affiliation:
Department of Geophysics & Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1W5Canada

Extract

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Stellar seismology of δ Scuti stars offers the best prospect for determining the interior properties of normal non-magnetic A-F stars on or near the main sequence. The discovery of rich eigenfrequency spectra in the light variations of several δ Scuti stars (e.g., θ2 Tau: Breger et al. 1989; GX Peg: Michel et al. 1990) should make this possible for low-degree modes (l ≤ 4). However, due to cancellation effects, modes of higher l cannot be studied through photometry or radial velocity measurements.

The detection of rapid line-profile variations among rapidly rotating δ Scuti stars (e.g., Walker et al. 1987; Kennelly et al. 1992) has extended our sensitivity to much higher modes. These variations are consistent with moderate- to high-degree modes, where |m| ~ l. (In the simplest case, they could be pure sectorial modes with |m| = l and pulsation amplitudes strongly confined to the stellar equator.) To use these data effectively, we need an objective way to identify the modes and their time evolution.

Type
VIII. Asteroseismology: observation
Copyright
Copyright © Astronomical Society of the Pacific 1993

References

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