Pre-supernova Evolution and the Fates of Massive Stars

Thu, April 09, 2015

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A confluence of recent observations in the past decade have indicated that some basic assumptions that have guided our understanding of massive stars are not correct.  On the one hand, models for single massive star evolution seem to have overestimated the effects of mass loss through winds and the influence of rotation.  On the other hand, observations have shown that a large fraction of massive stars are in close binaries that will exchange mass, and that these will dominate the observed statistical distributions of stars and supernova types.  This requires us to revise some long-held assumptions about the fates of massive stars, but it also helps us understand some observations of massive stars and supernovae that were problematic before.  One of these long-held paradigms concerns the role of luminous blue variables (LBVs), which are the brightest stars in any large star-forming galaxy.   LBVs have been thought to play the key role in removing the H envelopes of massive stars before they die as Wolf-Rayet stars, but a look at LBV environments paints a very different picture for the late phases of massive star evolution.  This talk will discuss LBVs, as well as the corresponding implications for understanding various types of supernovae that result from the deaths of massive stars.