GODDARD HIGH-RESOLUTION SPECTROGRAPH OBSERVATIONS OF THE INTERACTING BINARY-SYSTEM W-SERPENTIS

Spectroscopic observations of the interacting binary system W Serpenti s have been made at two orbital phases using the Goddard High-Resoluti on Spectrograph (GHRS) aboard the Hubble Space Telescope (HST). Differ ences in Si IV 1393, 1403 lambda lambda emission-line strengths and pr ofile shapes observed between the two phases suggest that a hot spot e xists where the giant stellar companion has transferred mass to an acc retion disk surrounding the mass-gaining component. Moreover, strong a bsorption features superposed on the Si IV emission lines indicate tha t the accretion disk is geometrically and optically thick. These absor ption features have been modeled to constrain the physical conditions of the disk.