Radiative winds in supersoft X-ray sources with passive disks

In supersoft X-ray sources (SSXSs) the central source, which is supposed to be a nuclear-burning white dwarf, is very luminous. In such a case the central luminosity (nuclear energy) dominates the disk luminosity (accretion energy). Therefore, the surrounding disk is not active, but passive, in the sense that irradiation heating dominates viscous heating. We examined the radiative environment and radiatively accelerated winds in such luminous SSXSs with passive disks. The radiation fields are generally enhanced in the polar direction due to the existence of the disk. We found that the wind configuration bifurcates according to the origin of wind gas; the wind tends to be a polar flow if it originates from the central star, whereas it becomes equatorial flow if it originates from the disk. The latter disk winds blow off the surface of the disk, confined in the vertical direction by the radiation fields. In both cases the terminal speed of the wind is of the order of root GM(Gamma-1)/R*, where M is the white-dwarf mass, R*, the white-dwarf radius, and Gamma the white-dwarf luminosity normalized by the Eddington luminosity. The polar flow is slightly faster than the equatorial flow, reflecting the bipolarity of radiation fields and the mass evaporation from the disk.