X-ray nova binary systems

The physical properties of X-ray novae as close binary systems are analysed . Observational data in X-ray, UV, optical, IR and radio ranges are summari zed. Modern theoretical considerations of the problem of X-ray novae, takin g into account some new ideas and results, are described. Properties of opt ical stars in X-ray novae are analysed. Data about the masses of black hole s in X-ray binary systems are summarized. Possible evolutionary links betwe en WR stars in close binary systems and X-ray novae are analysed.