Metal-poor stars in the Galactic bulge

Tuesday, 12 December 2023 7 a.m. — 8 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
Andrea Kunder (Saint Martin's University)

The origin of the metal-poor ([Fe/H] < -1.0 dex) stellar population in the bulge, which likely consists of some of the oldest stars in the inner Galaxy, is still not well understood.  I will discuss recent results from two surveys, BRAVA-RR and MWBest, that are probing the origin of the metal-poor bulge.  BRAVA-RR uses RR Lyrae stars as Galactic tracers, as RR Lyrae stars trace the earliest significant star formation events that contribute to the Milky Way, having predominantly formed when just ~0.5% of the stars in the present-day Milky Way had formed.  New radial velocity measurements, metallicity measurements, and orbital information for inner Galaxy RR Lyrae stars are used to place constraints on chemo-dynamical models of the metal-poor bulge.  MWBest is a spectroscopic survey with the goal of identifying stripped globular cluster stars from inner Galaxy clusters.  In this way, an indication on the fraction of bulge metal-poor stars that have originated from globular clusters can be determined.