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Session 38 - Disks and Bipolar Outflows from Hot Stars.
Display session, Tuesday, June 11
Tripp Commons,

[38.01] Inhibition of Wind Compressed Disk Formation by Nonradial Line-Forces

S. Owocki, K. Gayley, S. Cranmer (Bartol Research Institute, U. of Del.)

We investigate the effects of nonradial line-forces on the formation of a ``Wind Compressed Disk'' (WCD) around a rapidly rotating B-star. Such nonradial forces can arise from both asymmetries in the line resonances in the rotating wind, as well as from rotational distortion of the stellar surface. They characteristically include an azimuthal force component acting against the sense of rotation, and a latitudinal force component directed away from the equator. Here we present results from radiation-hydrodynamical simulations showing that these nonradial forces can lead to a significant spin-down of the wind rotation, as well as an effective suppression of the equatorward flow needed to form a WCD.

The qualitative sense of these effects can be understood from simple physical arguments and analytic test cases, though further testing and analysis is still needed to confirm their quantitative importance. Nonetheless, these results indicate that nonradial force components can effectively inhibit equatorial wind compression in a line-driven outflow. If confirmed, these effects would seriously undermine the WCD paradigm as an explanation for disk formation around Be and other rapidly rotating hot stars with line-driven stellar winds.

Program listing for Tuesday