Hydrodynamical Models of Line‐driven Accretion Disk Winds

We present here one-dimensional analytic hydrodynamic models and both one-dimensional and two-dimensional numerical hydrodynamic models for line-driven accretion disk winds from cataclysmic variable (CV) systems. Using the one-dimensional analytic models we explore the physical conditions necessary for the existence of a disk wind and study the dependence of wind speed and mass-loss rate on radius. The results of our two-dimensional model are consistent with the spectrum observed from CVs in the polar nature of the wind, the maximum absorption at roughly half the terminal speed of the P Cygni profiles, and the order of magnitude of the terminal speeds. For disk luminosity Ldisk = L☉, white dwarf mass Mwd = 0.6 M☉, disk radius Rdisk = R☉, and sound speed a = 10 km s-1 we obtain a wind mass-loss rate of wind=2 × 10−14 M yr-1 and a terminal velocity of ~3000 km s-1. The two-dimensional models show that centrifugal forces produce shocks in the disk wind. If these shocks were absent, the mass-loss rates obtained would be too low to produce the optical depths required to explain the P Cygni profile of CVs. The two-dimensional models demonstrate the importance of centrifugal forces in winds from accretion disks and thus the necessity of models where these forces may be represented.