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The X-ray variability of Vela X-1 (3U 0900-40)From observations of Vela X-1 with the MSSL 2.5-7.5 keV detector onboard Copernicus, the behavior of the source can be characterized by three phases: (1) high intensity, (2) low intensity, and (3) eclipse. Combining data from the 1972 Uhuru observations with eclipse observation yields a binary period of 8.963 + or - 0.001 days with zero phase on 1975 Feb. 6.97 + or - 0.04 UT. The low intensity phase is interpreted as being due to increased absorption in an accretion wake traveling across the line of sight (the spectral slope remains relatively constant throughout the cycle). Another period of enhanced absorption immediately after exit from eclipse may be due to a bow shock. Comparison of the two observations suggests that these structures vary from cycle to cycle and, since the orbital period is long, probably during each cycle.
Document ID
19760019022
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Charles, P. A.
(University Coll. London, United Kingdom)
Mason, K. O.
(University Coll. London, United Kingdom)
Culhane, J. L.
(University Coll. London, United Kingdom)
Sanford, P. W.
(University Coll. London, United Kingdom)
White, N. E.
(University Coll. London, United Kingdom)
Date Acquired
August 8, 2013
Publication Date
January 1, 1976
Publication Information
Publication: NASA. Goddard Space Flight Center X-ray Binaries
Subject Category
Astrophysics
Accession Number
76N26110
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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