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Ultraviolet, X-ray, and infrared observations of HDE 226868 equals Cygnus X-1During April, May, and July of 1978, HDE 226868, the optical counterpart of Cygnus X-1, was repeatedly observed in the ultraviolet with the IUE satellite. Some X-ray and infrared observations have been made during the same period. The general shape of the spectrum is that expected from a late O supergiant. Strong absorption features are apparent in the ultraviolet, some of which have been identified. The equivalent widths of the most prominent lines appear to be modulated with the orbital phase. This modulation is discussed in terms of the ionization contours calculated by Hatchett and McCray, for a binary X-ray source in the stellar wind of the companion.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Treves, A.
(Milan Univ. Italy)
Chiappetti, L.
(Milano, Universita Milan, Italy)
Tanzi, E. G.
(CNR Laboratorio di Fisica Cosmica e Technologie Relative, Milan, Italy)
Tarenghi, M.
(European Southern Observatory Geneva, Switzerland)
Gursky, H.
(Milan Univ. Italy)
Dupree, A. K.
(Milan Univ. Italy)
Hartmann, L. W.
(Milan Univ. Italy)
Raymond, J.
(Milan Univ. Italy)
Davis, R. J.
(Milan Univ. Italy)
Black, J.
(Harvard-Smithsonian Center for Astrophysics Cambridge, Mass., United States)
Date Acquired
August 11, 2013
Publication Date
December 15, 1980
Publication Information
Publication: Astrophysical Journal
Subject Category
Accession Number
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