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Line profile variations in γ Equ: A puzzle

Published online by Cambridge University Press:  12 April 2016

Hiromoto Shibahashi ,
Don Kurtz ,
Eiji Kambe  and
Douglas Gough
Hiromoto Shibahashi
Affiliation:
Department of Astronomy, University of Tokyo, Tokyo 113-0033, Japan
Don Kurtz
Affiliation:
Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK
Eiji Kambe
Affiliation:
Department of Earth and Ocean Sciences, National Defence Academy, Yokosuka, Kanagawa 239-8686, Japan
Douglas Gough
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK

Abstract

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Line profile variations in γ Equ show the classic blue-to-red travelling bumps of m-modes resolved by rotation, and they have been identified as l = 2 or 3, m = −l or −l + 1 by characterising the line shapes using the moment method. The mode identifications cannot be correct, however, since γ Equ is an extremely slowly rotating star (Prot > 70 yr). We propose an alternative interpretation, according to which the observed line profile variations are a manifestation of a shock wave in the high atmosphere near the magnetic polar regions; the oscillation mode is then still consistent with the photometric observations.

Type
Part 4. Early-type stars: B, A and F pulsators
Information
International Astronomical Union Colloquium , Volume 193: Variable Stars in the Local Group , 2004 , pp. 287 - 291
Copyright
Copyright © Astronomical Society of the Pacific 2004

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