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Hydrodynamical Models of Line-driven Accretion Disk Winds

Pereyra, Nicolas Antonio; Kallman, Timothy R.; Blondin, John M.
*Published in:*
ApJ, 477, 368

### Abstract

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&sun;, white
dwarf mass Mwd = 0.6 M&sun;, disk radius Rdisk = R&sun;, and sound speed a = 10
km s-1 we obtain a
wind mass-loss rate of M dot _{{wind}}=2{x10}^{-14} M_{solar} 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.