Astronomy Seminar: Irina Plaks (ISU)
Speaker: Irina Plaks (ISU)
Title: Probing Galaxy Evolution Using RR Lyrae Stars
Abstract: Studying stellar populations in the Local Group provides us with a means to constrain early galaxy evolution. RR Lyrae stars, very old (~10 Gyr) pulsating variables located on the horizontal branch, are one such stellar population. In addition to their more commonly known use as standard candles, RR Lyraes (RRLs) are an excellent tool to study the early evolutionary history of a galaxy. In this talk, I will discuss the observation and analysis of RRLs in M31 satellite galaxies.
As members of the Local Group, the Milky Way and M31 subsystems have likely been bound since early epochs. Despite this, there are disparities between the Milky Way and M31 galaxies, particularly in their star formation histories – disparities that extend to their respective satellites –raising the possibility of differing evolutionary histories. More specifically, M31 shows signs of recent accretion, whereas the Milky Way was formed by mergers during its early epochs. Analyzing the properties of RRLs in M31 satellites provides insight into their star formation and early chemical enrichment with the goal of explaining these disparities. This can, in turn, reveal information about the Local Group’s global formation and early evolution.