Presentation #314.04 in the session “Variable Stars I”.
Studying stellar populations in the Milky Way’s halo is one of several ways that astronomers can gain insight into how the halo formed. By studying the abundances, kinematics, and spatial distributions of the RR Lyrae population, a very old (10 Gyr) group of variable stars with a particularly short period of less than a day, researchers can understand the conditions present during the galaxy’s formation. These stars are ideal for observation due to their narrowly defined absolute magnitude and distinctive light curves. With recent advances in technology and the construction of new telescopes, astronomers now have the opportunity to perform more detailed studies on relatively distant (RGC > 3kpc) inner halo RR Lyrae. Using data from the All-Sky Automated Survey for SuperNovae (ASAS-SN), updated periods have been found for the ~100 RR Lyrae variables studied in Layden (1998). With these periods, updated light curves were obtained, providing accurate mean magnitudes, epochs of maximum light, and amplitudes. This updated information, as well as spectroscopic data, was used to find the distances, radial velocities, and metal abundances of these same stars, providing metallicities and kinematic properties for this old stellar population.