Astrophysics Seminar: Dr. Roman Gerasimov, University of Notre Dame

It is tempting to assume that stars born in the same environment would have nearly identical chemical compositions. Yet, this assumption is defied by globular clusters (GCs) that display significant member-to-member abundance variations. The patterns in GC abundances are not observed anywhere else in the galaxy, and cannot be self-consistently explained by any proposed enrichment mechanism. The study of this so-called issue of multiple populations dates back over a hundred years; however, only with the advent of space-based observations has it become possible to explore the GC chemical anomalies beyond their brightest members.

 

In this seminar, I will discuss new constraints on the origin of multiple populations in GCs, derived from high-precision HST photometry of the lower main sequence. I will also forecast upcoming observations with JWST that will, for the first time, reveal the brown dwarf members of nearby GCs. These new measurements will provide independent estimates of cluster ages and chemical abundances that will be uniquely suited to differentiate between the physical processes that may be contributing to the chemical complexity of GCs.