Journal Article

Combination frequencies in <i>δ</i> Scuti stars

L. A. Balona

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 422, issue 2, pages 1092-1097
Published in print May 2012 | ISSN: 0035-8711
Published online April 2012 | e-ISSN: 1365-2966 | DOI:
Combination frequencies in δ Scuti stars

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We consider the possible use of combination frequencies seen in high-amplitude δ Scuti stars for mode identification. For this purpose, we extend a previous theory to obtain expressions for the relative amplitudes and phases of combination frequencies for the case where radius and surface normal variations are important. Although a term is present which is sensitive to the pulsation mode, this term is always combined with another one which depends on the physics of the outer layers. Whereas the terms can be separated in DA and DB white dwarfs using suitable assumptions, these assumptions are not valid in pulsating main-sequence stars. We also discuss the strong correlation of relative phase of the combination frequencies with frequency. We show that this correlation is a result of the non-sinusoidal nature of the dominant pulsation mode.

Keywords: asteroseismology; stars: oscillations; stars: variables: δ Scuti

Journal Article.  4163 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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