X-ray and ultraviolet spectroscopy of CYG X-1 = HDE 226868.
White, N. E.; Kondo, Y.; McCluskey, G. E.; Becker, R. H.; Pravdo, S. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.
United States
Abstract
Observations of Cygnus X-1 with the solid-state spectrometer on the Einstein Observatory are presented. The X-ray spectra of two intensity dips viewed near superior conjunction did not exhibit increased photoelectric absorption. Rather, the data support a model in which an increase in the electron-scattering optical depth modifies both the observed spectrum and the intensity. The characteristic temperature of the intervening material is greater than about 50 million K. These measurements were in part simultaneous with observations by IUE. The ultraviolet spectrum and intensity remained relatively constant during an X-ray intensity dip.