New Near-Infrared Period-Luminosity-Metallicity Relations for Galactic RR Lyrae Stars Based on Gaia EDR3 Parallaxes

Bartłomiej Zgirski, Grzegorz Pietrzyński, Marek Górski, Wolfgang Gieren, Piotr Wielgórski, Paulina Karczmarek, Gergely Hajdu, Megan Lewis, Rolf Chini, Dariusz Graczyk, Mikołaj Kałuszyński, Weronika Narloch, Bogumił Pilecki, Gonzalo Rojas García, Ksenia Suchomska, Mónica Taormina

Published 2023-05-16Version 1

We present new period-luminosity and period-luminosity-metallicity relations for Galactic RR Lyrae stars based on a sample of 28 pulsators located at distances up to $1.5$ kpc from the Sun. Near-infrared photometry was obtained at the Cerro Armazones Observatory and parallaxes were taken from the Gaia Early Data Release 3. Relations were determined for the 2MASS $JHK_s$ bands and the $W_{JK}$ Wesenheit index. We compare our results with other calibrations available in the literature and obtain very good agreement with the photometry of RR Lyraes from the Large Magellanic Cloud anchored using the distance to the Cloud, which based on detached eclipsing binaries. We find that the dependence of absolute magnitudes on metallicity of $0.070\pm 0.042$ mag/dex ($J-$ band) to $0.087 \pm 0.031$ mag/dex ($W_{JK}$ index) for the population of fundamental pulsators (RRab) that is in agreement with previously published phenomenological works. We perform a refined determination of distance to the LMC based on our new calibration and photometry from Szewczyk et al. (2008). We study the dependence of the fitted parameters of fiducial relations and the LMC distance on the systematic parallax offset.