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Ultraviolet light curves of V535 AraeThe light curve of V535 Ara is determined from observations of this long-period W UMa binary in the UV, and its gravity darkening is estimated. The UV colors and spectral type correspond to (B - V)0 = 0.24, or A8V, and imply that the star should have very little residual convection in its envelope. It is concluded that the gravity darkening is large, as in a radiative star, unless it is modified by circulation in the common envelope, or unless all stars this warm are convective. Four solutions are obtained to a combination of optical and UV light curves, two for high radiative gravity darkening, and two for low convective gravity darkening. The light curves were fitted equally well in all four cases, while in all but the one with low-gravity darkening and a hot inner face there was a rather large global temperature difference between the two stars. It is suggested that the W UMa binaries are found only at spectral types later than about A8 because their outer envelopes must be convective to transfer luminosity.
Document ID
19920036903
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Eaton, Joel A.
(Tennessee State University Nashville, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1991
Publication Information
Publication: Astrophysics and Space Science
Volume: 186
Issue: 1 De
ISSN: 0004-640X
Subject Category
Astrophysics
Accession Number
92A19527
Funding Number(s)
CONTRACT_GRANT: NAG5-1372
CONTRACT_GRANT: NAG5-599
Distribution Limits
Public
Copyright
Other

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