Tuesday, December 6, 2011

1112.0936 (Jorick S. Vink et al.)

Wind Models for Very Massive Stars in the Local Universe    [PDF]

Jorick S. Vink, J. M. Bestenlehner, G. Graefener, A. de Koter, N. Langer
Some studies have claimed the existence of a stellar upper-mass limit of 150 Msun. A factor that is often overlooked concerns the issue that there might be a significant difference between the present-day and the initial mass of the most massive stars - as a result of mass loss. The upper-mass limit may be substantially higher, possibly exceeding 200 Msun. The issue of the upper mass-limit will however remain uncertain as long as there is only limited quantitative knowledge of mass loss in close proximity to the Eddington (= Gamma) limit. For this reason, we present mass-loss predictions from Monte Carlo radiative transfer models for very massive stars up to 300 Msun. Using our new dynamical approach, we find an upturn or "kink" in the mass-loss versus Gamma dependence, at the point where our model winds become optically thick. These are the first mass-loss predictions where the transition from optically thin O-star winds to optically thick Wolf-Rayet winds has been resolved.
View original: http://arxiv.org/abs/1112.0936

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