The Solution Topology of LineDriven Stellar Winds
Abstract
The radiativelydriven wind theory of Castor, Abbott, & Klein (CAK theory) is now widely accepted as the mechanism producing the massloss from earlytype (OB) stars. The fluid equation describing the solar wind, which contains a socalled ``Xtype'' critical point, was first solved by Parker using an analysis of the solution topology of the differential equation describing the wind velocity; however, the CAK wind equation is a nonlinear equation for the velocity gradient, so the origin and nature of the topology of the CAK critical point has been unclear. Employing a commonly used change of variables, we obtain a linear differential equation whose solution topology is easily found. We show that in fact the CAK critical point is indeed an Xtype singularity like the Parker critical point. We also find that there are four previously unknown critical points (two of these are unphysical). In addition to the transcritical solution found by CAK, which has a monotonically increasing velocity, there are subcritical nonmonotonic solutions, analogous to the Chamberlain breeze solutions for the solar wind, as well as a transcritical monotonically decreasing solution. However, the only outflow solution that satisfies the boundary condition of zero pressure at infinite radius is the original CAK solution. Thus the new solutions are relevant only for accretion flows fed by an external source such as a masstransfer binary.
 Publication:

American Astronomical Society Meeting Abstracts
 Pub Date:
 December 1994
 Bibcode:
 1994AAS...185.8010B