On the Road to the Supernova: LBVs, Hypergiants, and SN Impostors

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This award will fund a combined observational and theoretical study of luminous blue variables, which are massive stars experiencing strong mass loss and evolving to be red supergiants. They are widely believed to the progenitors of core-collapse supernovae, but many of these may not explode if the mass lost during their lifetimes is high enough. This team will conduct long-term observations of these variables in several nearby galaxies, in order to get an improved census of these objects, elucidate the mechanisms that may be responsible for giant eruptions, and to better understand the mechanism of mass loss and how stars evolve as they experience episodic (rather than steady) mass loss.Modern supernova surveys are finding a number objects in nearby galaxies which are not true supernovae, the "supernova impostors," which may be objects like eta Carinae that shed 10-20 times the mass of our Sun in a few years. The final stages of these most massive stars are important for a valid picture of stellar astrophysics and they are increasingly significant in cosmology. They are the likely progenitors of Gamma Ray Bursters used as cosmological probes, and many of the first stars in the universe are thought to have been very massive.