A consistent solution for the velocity field and mass-loss rate of massive stars

Patrick E. Mueller (1), Jorick S. Vink (2)

(1) Keele University, UK
(2) Armagh Observatory, Northern Ireland, UK

Stellar winds are an important aspect of our understanding of the evolution of massive stars
and their input into the interstellar medium. Here we present solutions for the velocity
field and mass-loss rates for stellar outflows as well as for the case of mass accretion
through the use of the so-called Lambert W-function. For the case of a radiation-driven
wind, the velocity field is obtained analytically using a parameterised description for
the line acceleration that only depends on radius, which we obtain from Monte-Carlo multi-
line radiative transfer calculations. In our form of the equation of motion the critical
point is the sonic point. We also derive an approximate analytical solution for the
supersonic flow which closely resembles our exact solution. For the simultaneous solution of
the mass-loss rate and velocity field, we describe a new iterative method. We apply our
theoretical expressions and our iterative method to the stellar wind from a typical O5-V main
sequence star, and find good agreement with empirical values. Our computations represent the
first self-consistent mass-loss calculations including the effect of multi-line scattering for
an O-type star, opening up the possibility of applying Monte Carlo mass-loss calculations in
regions of the Universe for which empirical constraints cannot be readily obtained.

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

Weblink: http://arXiv.org/abs/0810.1901


Email: pmueller@astro.keele.ac.uk