Bright single-mode RR Lyrae stars: Matching Gaia EDR3 with pulsation and evolutionary models

Abstract

We combine observed metallicity, optical, and infrared magnitudes with evolutionary and pulsation models to derive average luminosities for 156 single-mode RR Lyrae stars. These luminosities are compared with those obtained from the Gaia EDR3 parallaxes and are found to be in excellent agreement with the high accuracy subsample (62 stars, with relative parallax errors of less than 2%). With the temperature and metallicity scale used, no parallax shift seems to be necessary when α-enhanced evolutionary models are employed. Some 10% of the sample shows curious “distance keeping” between the evolutionary and pulsation models. The cause of this behavior is not clear at this moment but can be cured by an excessive increase in the reddening.