Chemical Abundances of Halo Stars in the Sloan Digital Sky Survey V

This project explores the origins of our Milky Way galaxy by identifying and analyzing stars in its “stellar halo”, which is composed of remnants of small dwarf galaxies that were torn apart by the Milky Way’s gravity long ago. A team of scientists at the University of Chicago will use data from the Sloan Digital Sky Survey (SDSS) to study the chemical fingerprints of these stars. The goal is to reconstruct the Milky Way’s early assembly and search for signatures of the first supernovae in the universe. Undergraduate students will carry out significant portions of this research as part of an astronomy field course at the University of Chicago. The project also includes a collaboration with a non-R1 institution to engage students in studying pulsating halo stars. Educational materials from both efforts will be publicly shared through the SDSS Education and Public Outreach platform. The halo stars will be selected from the SDSS-V halo star survey, which uses low-resolution spectroscopy of photometrically metal-poor stars to measure iron and alpha-element abundances. Most halo stars come from a few massive accretion events, which are already well-characterized. This project instead focuses on the frontier of lower-mass accreted galaxies, traced by low-alpha, metal-poor stars (LAMPS). Approximately 400–500 LAMPS will be followed up with high-resolution optical spectroscopy, enabling the measurement of abundances for 20+ elements per star. These data will support studies of r-process nucleosynthesis, Type Ia supernova origins, and potentially remnants of Population III explosions such as pair-instability supernovae. Undergraduate students will be fully integrated into the research process, from target selection to observing and abundance analysis. The PI will also collaborate with a Faculty and Student Team at California State University San Bernardino to measure the Milky Way’s mass using RR Lyrae stars and develop tutorials for accessing public SDSS-V data. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.