High-Resolution Spectroscopy of Extremely Metal-Poor Stars in the Least Evolved Galaxies: Ursa Major II and Coma Berenices

Understand

We present Keck/HIRES observations of six metal-poor stars in two of the ultra-faint dwarf galaxies orbiting the Milky Way, Ursa Major II and Coma Berenices.

• These observations include the first high-resolution spectroscopic observations of extremely metal-poor stars ([Fe/H]<-3.0) stars not belonging to the Milky Way (MW) halo field star population.
• We obtain abundance measurements and upper limits for 26 elements between carbon and europium.
• The entire sample of stars spans a range of -3.2<[Fe/H]<-2.3, and we confirm that each galaxy contains a large intrinsic spread of Fe abundances.