H-alpha variability in X-ray transient source X0331+53.

Abstract

Spectroscopic observations of X0331+53 between October 1984 and March 1985 revealed that the equivalent width of Hα emission decreased by a factor of about four relative to that observed one year ago. This finding, in association with the decline of X-ray activity of the source reported by the EXOSAT group, is interpreted to support the binary model of an OB star and a pulsar in which the Hα emission originates in a direct vicinity of the massive primary star.