Accretion Disk and Boundary Layer Models Incorporating Opal Opacities

Abstract

According to standard analytical models, the continuum spectrum of an accretion disk is independent of the opacity. To test this result more generally, we have constructed vertically averaged, optically thick models for accretion disks and boundary layers in cataclysmic variables. We compare models constructed using a constant electron scattering opacity to those computed with the OPAL tabulated Rosseland mean opacity. We verify that the continuum spectrum emitted from the disk is independent of the opacity, and we find that the continuum spectrum emitted from the boundary layer shows a small dependence on the opacity. This results in an increase in the boundary layer luminosity for the OPAL model of approximately a factor of 2.5. However, the central temperature and disk width are also quite different, implying that models with different opacities have different thermal timescales and perhaps different oscillation properties.