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Short-period Variations of 28 CMa during 1998/9

Published online by Cambridge University Press:  12 April 2016

L.A. Balona  and
D. James
L.A. Balona
Affiliation:
South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape Town, South Africa
D. James
Affiliation:
School of Physics and Astronomy, University of St. Andrews, Scotland

Abstract

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The Be star 28 CMa was one of the first periodic Be stars to be discovered and shows very large line profile variations with a period of 1.37 d. Recently, it has been shown that the line profile and light variations can be modeled by a patch of gas suspended above the photosphere. We present echelle observations of the Hβ and Hϒ line and several helium and metal absorption lines. We show that the radial velocity variations of these lines are unchanged since they were first observed two decades ago. We also examined several emission lines of Fe II and show that they do not partake of the periodic variation. We attribute the periodic variations of the lines formed close to the photosphere to a co-rotating cloud, whereas the Fe II emission lines are formed in the circumstellar disk outside the co-rotating radius.

Type
3. Periodic Variations
Information
International Astronomical Union Colloquium , Volume 175: The Be Phenomenon in Early-Type Stars , 2000 , pp. 236 - 239
Copyright
Copyright © Astronomical Society of the Pacific 2000

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