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Ultraviolet light curves of beta Lyrae: Comparison of OAO A-2, IUE, and Voyager ObservationsThe six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory (OAO) A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO A-2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.
Document ID
19950035537
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kondo, Yoji
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mccluskey, George E.
(Lehigh Univ. Bethlehem, PA, United States)
Silvis, Jeffery M. S.
(Catholic Univ. Washington, DC, United States)
Polidan, Ronald S.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mccluskey, Carolina P. S.
(Pennsylavania State Univ. Fogelsville, PA, United States)
Eaton, Joel A.
(Tennessee Sate Univ. Nashville, TN, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 421
Issue: 2
ISSN: 0004-637X
Subject Category
Astronomy
Accession Number
95A67136
Distribution Limits
Public
Copyright
Other

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