Dynamics of Line‐driven Winds from Disks in Cataclysmic Variables. II. Mass‐Loss Rates and Velocity Laws

We analyze the dynamics of 2D stationary line-driven winds from accretiondisks in cataclysmic variables (CVs), by generalizing the Castor, Abbott andKlein theory. In paper 1, we have solved the wind Euler equation, derived itstwo eigenvalues, and addressed the solution topology and wind geometry. Here,we focus on mass loss and velocity laws. We find that disk winds, even inluminous novalike variables, have low optical depth, even in the strongestdriving lines. This suggests that thick-to-thin transitions in these linesoccur. For disks with a realistic radial temperature, the mass loss isdominated by gas emanating from the inner decade in r. The total mass loss rateassociated with a luminosity 10 Lsun is 10^{-12} Msun/yr, or 10^{-4} of themass accretion rate. This is one order of magnitude below the lower limitobtained from P Cygni lines, when the ionizing flux shortwards of the Lymanedge is supressed. The difficulties with such small mass loss rates in CVs areprincipal, and confirm our previous work. We conjecture that this issue may beresolved by detailed nonLTE calculations of the line force within the contextof CV disk winds, and/or better accounting for the disk energy distribution andwind ionization structure. We find that the wind velocity profile is wellapproximated by the empirical law used in kinematical modeling. Theacceleration length scale is given by the footpoint radius of the windstreamline in the disk. This suggests an upper limit of 10 Rwd to theacceleration scale, which is smaller by factors of a few as compared to valuesderived from line fitting.