ULTRAVIOLET LINE DIAGNOSTICS OF ACCRETION DISK WINDS IN CATACLYSMIC VARIABLES

The IUE data base is used to analyze the UV line shapes of the catacly smic variables RW Sex, RW Tri, and V Sge. Observed lines are compared to synthetic line profiles computed using a model of rotating biconica l winds from accretion disks. The wind model calculates the wind ioniz ation structure self-consistently including photoionization from the d isk and boundary layer and treats three-dimensional line radiation tra nsfer in the Sobolev approximation. It is found that winds from accret ion disks provide a good fit for reasonable parameters to the observed UV lines which include the P Cygni profiles for low-inclination syste ms and pure emission at large inclination. Disk winds are preferable t o spherical winds which originate on the white dwarf because they (1) require a much lower ratio of mass-loss rate to accretion rate and are therefore more plausible energetically, (2) provide a natural source for a bi-conical distribution of mass outflow which produces strong sc attering far above the disk leading to P Cygni profiles for low-inclin ation systems and pure line emission profiles at high inclination with the absence of eclipses in UV lines, and (3) produce rotation-broaden ed pure emission lines at high inclination.