Joseph Mullen, ISU

RR Lyrae stars (RRls) are radially pulsating stars that are widely used tracers of old (age > 10 Gyr) stellar populations in the Milky Way and Local Group galaxies. The number of known RRLs has significantly increased with the advent of large area photometric sur- veys. However, RRLs with known metal abundances remain limited due to the reliance on spectra, which require large amounts of tele- scope/analysis time. This work seeks to calibrate a quick and reliable method to derive metallicities solely from readily available photomet- ric time series, as the shape of RRLs light curve is inherently tied to its metallic abundance. We present our newly published period- Fourier-metallicity relations in both the optical and, for the first time, mid-infrared. This work will allow metallicity measurements to be made in both high-extinction environments and at much larger distances.