Jason Kalirai, Space Telescope Science Institute, Baltimore

Topic: "Stellar Evolution, Mass Loss, and Dead Stars"  (Video)

ABSTRACT:The total stellar mass loss that a star suffers through post main-sequence evolution is of vital importance to understand its subsequent evolution. The mass loss rate along the first ascent red giant branch alone determines the upper RGB luminosity function and the horizontal branch morphology. The distribution of stars in these phases directly affects our interpretation of the integrated colors of distant galaxies, and therefore is of fundamental importance to galaxy formation and evolution studies in the higher redshift Univese. Yet, these mass loss rates, especially as a function of age and metallicity, are very poorly constrained in current models. I will present new constraints on this field based on imaging and spectroscopic observations of the final end products from this evolution, white dwarfs. By studying the mass distribution of these dead stars in nearby stellar populations with a range of (known) ages and metallicities, we can directly constrain the mass loss rates of stars across a range of environments. These observations directly impact several fields in astrophysics including our knowledge of the enrichment of the interstellar medium, our ability to construct population synthesis models to interpret galaxy colors, and the general interpretation of the sources and processes responsible for the observed UV-upturn in elliptical galaxies.