Astronomy Tea Talk
Speaker 1: Aliza Beverage
Title: The chemical compositions of massive quiescent galaxies across cosmic time with JWST
Abstract:
One of the most remarkable discoveries since the launch of JWST is that massive galaxies formed more rapidly and quenched earlier than expected. Stellar metallicities and chemical abundances provide critical insight into these galaxies' star formation and assembly histories. Measuring these properties is challenging, but recent ultra-deep spectroscopic surveys are finally opening a window into studying this population. In this talk, I will present results from our JWST/NIRSpec SUSPENSE program, targeting 20 massive quiescent galaxies at z=1-3. These galaxies display non-solar abundance patterns indicating extreme star-formation histories and rapid quenching by z~4. Such extreme elemental abundances are unlike any found at z~0, suggesting that the population of massive quiescent galaxies has evolved significantly over the last 11 billion years.
Speaker 2: Alex Raroche
Title: The first sample of orbital properties for stars stripped in binaries: towards population statistics
Abstract:
Massive stars govern a variety of astrophysical phenomena, ranging from galactic evolution through chemical enrichment via stellar winds and supernova explosions, to the production of gravitational wave sources through compact object formation. While a third of all massive stars have been predicted to undergo mass transfer induced envelope stripping, it was only recently that the first population of stripped stars were discovered in the Magellanic Clouds. Now, for the first time, we are able to study the properties of stripped stars in the mass gap between subdwarfs and Wolf-Rayet stars. I will describe the progress to date in discovering and characterizing the first sample of stripped stars, from the detection method to their stellar properties. I will then present ongoing work to measure the orbital properties of stripped star binaries with an observing campaign now spanning more than half a decade. I will present stripped star orbital parameter distributions in comparison to other massive binary populations, comment on the nature of the binary companions to stripped stars (a compact object or luminous companion), and the mass transfer which may have produced a subset of our observed sample. Finally, I will describe how our observations fit into the broader stripped star landscape, and the exciting work ahead as we transition from a dearth of stripped stars to large observational samples.