University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, October 21st 2016
Speaker: Nathan Smith, U of Arizona, Steward Observatory
Subject: Blast waves in circumstellar gas, and implications for the pre-supernova evolution of massive stars

The interaction between a supernova blast wave and dense circumstellar material (CSM) provides a unique way to investigate the very latest-phases in the pre-core collapse evolution of massive stars, because mass shed by the star in the preceding decade is illuminated and shock heated. Recent studies of such supernovae have shown that these late phases of stellar evolution must, in some cases, be punctuated by violent instabilities that precede the supernova by a few years to decades. The cause of these and the types of stars which fall subject to the instability remains as an open question, but depending on the explosion energy and the mass distribution of CSM, the conversion of kinetic energy into light can produce some of the most luminous supernovae in the universe. Because of high efficiency, this process can also produce moderately luminous transients even from non-terminal eruptions or low-energy explosions. Because many of these non-terminal eruptions can repeat, because low-energy explosions can come from relatively low-mass stars, and because some of the resulting supernovae are extraordinarily luminous, CSM interaction may figure prominently in the vast array of unusual transients now being discovered by transient searches (and by LSST in the future). The talk will explore the diversity of different transients that may result from CSM interaction, including a discussion of several individual observed examples that illustrate extremes in parameter space. I'll end with a very famous and very peculiar astronomical object, where a simple model of CSM interaction may help resolve some long-standing mysteries and paradoxes that have seen little progress in the last 30 years.

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