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The high energy X-ray spectrum of 4U 0900-40 observed from OSO 8The X-ray source 4U 0900-40 (= Vela XR-1) was observed with the high-energy X-ray spectrometer on OSO 8 for one week in 1976 and three weeks in 1978. Spectra of the source are presented above 16 keV. No systematic difference exists between the X-ray eclipse centers and the eclipse centers predicted from optical ephermerides. Short period intrinsic variability in the system's X-ray intensity may be related to changes in the Compton scattering optical depth in the system and does not require sporadic mass transfer via Roche lobe overflow. The 282 s modulation in the source's X-ray flux above 21 keV consists of two essentially similar pulses per period, most easily interpreted as arising from the two different magnetic poles of a rotating neutron star. The secondary appears to be a spherically accreting, magnetic neutron star.
Document ID
19820031729
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Dolan, J. F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Crannell, C. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dennis, B. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Frost, K. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Orwig, L. E. (NASA Goddard Space Flight Center Laboratory for Astronomy and Solar Physics, Greenbelt, MD, United States)
Ellison, D. C. (NASA Goddard Space Flight Center Laboratory for Astronomy and Solar Physics, Greenbelt, MD; Catholic University of America, Washingto, United States)
Date Acquired
August 10, 2013
Publication Date
November 1, 1981
Publication Information
Publication: Astrophysical Journal
Subject Category
ASTROPHYSICS
Distribution Limits
Public
Copyright
Other