The hot component of KS Persei /HD 30353/

The presence of a hot companion for the single-lined spectroscopic binary KS Per (HD 30353) has been detected in a study of low-resolution IUE spectra. The system as a whole is very similar to Upsilon Sgr. The observations are consistent with a model in which the primary is a helium supergiant of about 1 solar mass and the secondary is an overluminous early-type star with a mass of 5-6 solar masses. This model predicts that the system is now undergoing its second mass exchange.