New Frontiers in Stellar Astrophysics: Massive Stars as Cosmological Tools

University Of Washington, Seattle WA

Investigators

Abstract

Stars more than 10 times as massive as the Sun are important building blocks in our Universe. Their violent deaths in supernova explosions, in which stars are unable to hold themselves up against gravity, release new material into galaxies to form new stars. These massive stars are bright, and thus they hold promise as distance estimators to distant galaxies. If we know how bright a star should look, we can compare its apparent brightness to find its distance. Unfortunately, these stars are rare and thus poorly understood at the moment. The investigator plans to collect basic data about massive, luminous stars in other galaxies. The observations will help us better understand the lives of these stars. Both graduate and undergraduate students will take part in the research. She will also work with the Zooniverse Project to convert the light variations of astronomical objects---usually conveyed visually---to sound. This effort will be of interest to citizen scientists, particularly those who are visually impaired. The investigator describes a multi-wavelength observing plan that covers the post-main sequence phases of stellar evolution before the stars explode as supernovae. The ongoing HST COS far-UV SNAP program provides high S/N spectra, with better resolution, than were previously possible. The project will sample objects of different metallicity, including extremely-metal-poor galaxies, that will serve as analogs for star formation regions in the early Universe. The investigator will also create a comprehensive library of ultraviolet spectra using observations of 87 nearby star-forming galaxies, using these data to test the next generation of stellar population synthesis and photoionization codes.