Colloquium: Roberta Humphreys will introduce "the most interesting stars I know"
Professor Roberta Humphreys of the School of Physics and Astronomy will deliver the first colloquium of the 2021-2022 school year on the topic of Luminous Blue Variables (LBVs), rare, extremely large stars known as Hypergiants and their imposters.
Abstract: The most massive stars end their brief lives dramatically as supernovae when their massive cores collapse to black hole or neutron stars. Prior to their terminal state though, massive stars experience high mass loss episodes that alter their evolution and their eventual fate. Forty years ago, our comparison of the most luminous stars in our region of the Milky Way and the Large Magellanic Cloud revealed comparable populations of massive stars and the recognition of an empirical upper-luminosity boundary that was not predicted by theory or models at that time. Up until that time it was generally accepted that red supegiants were the end produce of massive stars evolution. But the lack of red supergiants above a certain luminosity implied an upper mass for stars that could evolve to red supergiants with important implications for stellar evolution. We suggested then that the upper luminosity boundary was due to mass loss, including high mass loss episodes near the Eddington limit. Today, observations in the Galaxy and nearby resolved galaxies have revealed evolved stars of different types experiencing high mass loss, stars that characterize the upper luminosity limit, and provide clues to the origin of their high mass loss events prior to their terminal state. These include the Luminous Blue Variables (LBVs), warm and cool hypergiants, B[e] supegiants, and “superpnova impostors”. I'll just have time to introduce you to some of the most interesting stars I know.