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Episodic dust formation in the wind of HD 193793

Published online by Cambridge University Press:  04 August 2017

P.M. Williams ,
K.A. Van der Hucht ,
D.R. Florkowski ,
A.M.T. Pollock  and
W.M. Wamsteker
P.M. Williams
Affiliation:
1. Royal Observatory, Blackford Hill, Edinburgh, Scotland
K.A. Van der Hucht
Affiliation:
2. SRON Laboratory for Space Research, Beneluxlaan 21, Utrecht, The Netherlands
D.R. Florkowski
Affiliation:
3. U.S. Naval Observatory, Washington, D.C. 20309, U.S.A.
A.M.T. Pollock
Affiliation:
4. Dept Space Reasearch, University of Birmingham, Birmingham, B15 2TT, England 5. ESA-EXOSAT Observatory, ESOC, Robert Bosch Strasse 5, 6100 Darmstadt, F.R.G.
W.M. Wamsteker
Affiliation:
6. ESA-IUE Tracking Station, Villafranca del Castillo, Madrid, Spain

Abstract

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In 1985 April, the WC7+abs star HD 193793 was observed, using UKIRT, to have brightened significantly in the infrared owing to the formation of a new dust shell. Examination of infrared photometry of this star since 1979 and previously published data indicates that the dust formation occurs at intervals of 7.9 years. Phasing the published radial velocities of the absorption line component with this period confirms that it is a member of an eccentric (e = 0.7−0.8) binary system having periastron passage shortly before dust formation. The X-ray spectrum also changed between 1984 and 1985 in becoming significantly “harder” while the non-thermal radio source disappeared, both changes indicating greater extinction. This suggests a model wherein the source of the non-thermal radio and X-ray emission moves deep into the Wolf-Rayet wind.

Type
Mass Loss from Hot Stars
Information
Symposium - International Astronomical Union , Volume 122: Circumstellar Matter , 1987 , pp. 453 - 454
Copyright
Copyright © Reidel 1987 

References

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