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A hot companion to Mu Sagittarii - An opportunity to sound the atmosphere of a B8 Ia supergiantIt is argued that the bright supergiant star Mu Sagittarii is accompanied by a smaller and hotter star, of spectral type approximately B1.5 V. The single-line radial-velocity curve of the B8 star leads to a fairly large mass function, f(m) = 2.64 solar masses, implying that the companion should have at least 50 percent of the mass of the visible star. Older optical observations indicated the presence of a shallow eclipse at the time of the conjunction with the supergiant behind the companion. Since the Copernicus, IUE, and Voyager observations show that the companion is the hotter component, that eclipse must have been the secondary eclipse (if it was an eclipse at all). A deeper, primary eclipse has been predicted by Plavec in 1978. It was indeed observed as a marked decrease of the far-ultraviolet flux from the system both with the Copernicus and the IUE satellites. The presence of a hotter but smaller component in Mu Sagittarii offers a unique opportunity to study the outer atmospheric layers of a supergiant which is of a much earlier spectral type than the supergiants in the Zeta Aurigae systems.
Document ID
19850032136
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Polidan, R. S.
(Arizona, University Tucson, AZ, United States)
Plavec, M. J.
(California, University Los Angeles, CA, United States)
Date Acquired
August 12, 2013
Publication Date
November 1, 1984
Publication Information
Publication: Astronomical Journal
Volume: 89
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
85A14287
Funding Number(s)
CONTRACT_GRANT: NSF AST-82-00046
Distribution Limits
Public
Copyright
Other

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