Variable Stars as Probes of Star Formation and Chemical Evolution of Galaxies

The study of resolved stellar populations in the Local Group and beyond is entering a new era of discovery, thanks to upcoming wide-area photometric surveys like Rubin/LSST and the Roman community surveys. Deep stellar catalogs across entire galaxies allow us to trace star formation and chemical evolution over cosmic time, providing essential input for hierarchical galaxy evolution models within the ΛCDM framework. However, this analysis is still limited by the age-metallicity degeneracy, which blurs the distinction between the star formation history of a galaxy and its chemical enrichment over time.Pulsating stars help overcome this degeneracy by providing strong metallicity constraints for stellar populations with well-defined ages. In this talk, I will present the methods we have developed to derive robust photometric metallicities for various types of pulsating stars (including RR Lyrae, long-period variables, and different classes of Cepheids), based on the shape of their optical and infrared light curves, as well as period-luminosity-metallicity relations. I will also share examples from our work on nearby dwarf galaxies, based on HST and JWST photometric datasets.