Light Curve Structure Reveals Fundamental Parameters of Cepheid and RR Lyrae Stars

The period of pulsation and the structure of the light curve for Cepheid and RR Lyrae variables depend on the fundamental parameters of the star: mass, radius, luminosity, and effective temperature. Here we train artificial neural networks on theoretical pulsation models to provide estimates of the fundamental parameters of these stars based on their period and light curve structure. We find that addition of light curve structure makes roughly a 70% improvement to estimates of these parameters. We apply our trained machine learning algorithms to OGLE-IV data for Cepheids and RR Lyraes in the Bulge, LMC and SMC, and obtain distances, masses and luminosities that are consistent with values quoted in the literature. We obtain distance moduli to the Magellanic Clouds of μ_LMC,CEP = 18.688±0.093, μ_LMC,RRL =18.52 ±0.14, and μ_SMC,RRL =18.88 ±0.17 mag.