Title: The Optical Properties of Binary Star Systems with Accretion Discs
Abstract: This paper derives a correlation between the period and the optical visibility of a hot spot on an accretion disc in a close binary system. X-ray binaries and rapid blue variables are considered. It is suggested that the emission line features and secondary pulses might be used to detect the existence of faint hot spots. In principle these observable features might be used to determine the mass ratio of the system and the relative size of the accretion disc. Possible sources of error, caused by uncertainties in the observation, are discussed. For the HZ Her–Her X-I system, the mass ratio is estimated and an explanation is given for the observed marching of the dips in the X-ray light curve.