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Detection of soft X-ray emission from SMC X-1The observation of 0.25-keV X-rays from SMC X-1 by a soft X-ray experiment aboard OSO 8 is reported. The variable soft X-ray source observed is identified with the hard X-ray source SMC X-1 on the basis of a rather abrupt ending to the emission (fall time about 2.5 hr) at the time SMC X-1 was expected to enter eclipse. A source luminosity of about 5 x 10 to the 38th erg/s in the 0.18-0.28-keV range is derived by assuming a distance of 68 kpc and correcting for attenuation by 3.4 x 10 to the 20th H atoms per sq cm of intervening galactic gas; this luminosity is shown to be about a factor of 40 greater than the observed coincident luminosity in the 0.8-3-keV band. The soft X-ray intensity upon emergence from eclipse is found to be reduced by a factor of at least 20 from the peak intensity prior to eclipse. It is suggested that this asymmetry may reflect a geometry in which the soft X-ray source trails the compact star as in an accretion-stream model.
Document ID
19790041811
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bunner, A. N.
(Wisconsin Univ. Madison, WI, United States)
Sanders, W. T.
(Wisconsin, University Madison, Wis., United States)
Date Acquired
August 9, 2013
Publication Date
February 15, 1979
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
79A25824
Funding Number(s)
CONTRACT_GRANT: NAS5-22410
Distribution Limits
Public
Copyright
Other

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