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A Multi-Site Study of The Extreme Helium Star V2076 Oph

Published online by Cambridge University Press:  12 April 2016

D.J. Wright ,
P.L. Cottrell ,
A.E. Lynas-Gray ,
D. Kilkenny  and
R. Shobbrook
D.J. Wright
Affiliation:
Department of Physics & Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
P.L. Cottrell
Affiliation:
Department of Physics & Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
A.E. Lynas-Gray
Affiliation:
Department of Physics, University of Oxford, Oxford OX1 3RH, UK
D. Kilkenny
Affiliation:
South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
R. Shobbrook
Affiliation:
School of Physics, University of Sydney, NSW 2006, Australia

Abstract

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Results from a three-site photometric and spectroscopic campaign of the hottest known extreme helium star V2076 Oph are presented. V2076 Oph shows complex multiple periods ranging from 0.3 to 3 d. However for the two campaigns in 1982 and 2000, no definitive single period can be identified in both datasets. Some of the extracted periods appear to be one-day aliases of others. The two most convincing periods are 0.52 d (22.28 mHz) and 2.75 d (4.21 mHz). The spectral lines identified in V2076 Oph were He I, He II, C II (emission), C III (both emission and absorption), C IV and N III. These lines showed profile variations that could not be linked to the photometric variations. Individual line velocities vary by species and ionisation level. The spectral lines vary in phase with an amplitude of ~25 kms−1 – the exception is the strong C III emission line at 5696 Å which shows different behaviour and has the lowest observed average velocity. This indicates that this emission line originates in the stellar wind rather than the photosphere.

Type
Part 9. Evolutionary and pulsation properties of variable stars
Information
International Astronomical Union Colloquium , Volume 193: Variable Stars in the Local Group , 2004 , pp. 539 - 542
Copyright
Copyright © Astronomical Society of the Pacific 2004

References

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