Structure and appearance of winds from supercritical accretion disks. I. Numerical models

This is the first of two papers that investigate models of radiation-driven winds from super-critical accretion disks. The main assumptions in the models are that the mass and luminosity in the wind emanate from the radius in the disk where accretion becomes supercritical (the critical radius) and that the wind is spherical. In this first paper the equations for disk and wind structure are derived and a steady-state hydrodynamic computer code is develoved and used to solve these equations with the same relaxation techniques used in stellar structure problems. The second paper derives analytic approximations to the results and applies them to various astrophysical systems. The models have four parameters; the mass of the accreting star M, the total accretion rate M/sub T/, α' (a generalized form of the original disk α parameter including heating by processes other than viscosity), and the ratio of the total luminosity to the Eddington luminosity GAMMA/sub T/.For accretion onto a hard-surfaced star, steady, optically thick winds result for even slightly supercritical accretion. The photosphere is typically approx.103 times the critical radius, hiding much or all of the disk and in some cases a binary companion as well. The object will appear as a supergiant star with a high mass loss rate and a non-blackbody spectrum. Transition from subcritical to supercritical accretion is expected to be a dynamical event, but eventually a stable wind should obtain even if ejection from an unstable disk occurs intermittently. Winds from black hole accretion disks may be somewhat different, but the differences will depend on the form of accretion interior to the critical radius. The nature of these wind indicates they should be applicable to a wide variety of accretion phenomena including cataclysmic and X-ray binaries and perhaps quasars