What physics sets the upper mass limit of stars?
Abstract: Basic stellar structure dictates that the luminosity of stars increases with a high power of the mass (roughly L~M3). For M > 100 Msun, the luminosity is so great that radiation pressure dominates the support of the stellar interior against gravity. Much as when a light fluid supports an overlying heavier one, this situation is thought to be susceptible to instabilities that can lead to episodes of enhanced brightness associated with extreme mass loss. This talk will review the radiation hydrodynamics of this mass loss, and discuss how it can impose an effective upper limit for stellar mass.
