Wind Models for Very Massive Stars in the Local Universe
Jorick S. Vink (Armagh), J. M. Bestenlehner (Armagh), G. Graefener (Armagh), A. de Koter (Amsterdam), N. Langer (Bonn)
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.
Reference: To appear in Four Decades of Research on Massive Stars, ASP Conf. Ser.
Status: Conference proceedings