Nonlocal radiative coupling in non monotonic stellar winds

A. Feldmeier and R. Nikutta

Potsdam University, Germany

There is strong observational evidence of shocks and
clumping in radiation-driven stellar winds from hot, luminous
stars. The resulting non monotonic velocity law allows for radiative
coupling between distant locations, which is so far not accounted for
in hydrodynamic wind simulations. In the present paper, we determine
the Sobolev source function and radiative line force in the presence
of radiative coupling in spherically symmetric flows, extending the
geometry-free formalism of Rybicki and Hummer (1978) to the case of
three-point coupling, which can result from, e.g., corotating
interaction regions, wind shocks, or mass overloading. For a simple
model of an overloaded wind, we find that, surprisingly, the flow
decelerates at all radii above a certain height when nonlocal
radiative coupling is accounted for. We discuss whether
radiation-driven winds might in general not be able to re-accelerate
after a non monotonicity has occurred in the velocity law.

Reference: A&A, in press
Status: Manuscript has been accepted