Metallicity of Galactic RR Lyrae from Optical and Infrared Light Curves. I. Period–Fourier–Metallicity Relations for Fundamental-mode RR Lyrae

• Published in: The Astrophysical journal Vol. 912; no. 2; pp. 144 - 161
• Main Authors: Mullen, Joseph P., Marengo, Massimo, Martínez-Vázquez, Clara E., Neeley, Jillian R., Bono, Giuseppe, Dall’Ora, Massimo, Chaboyer, Brian, Thévenin, Frédéric, Braga, Vittorio F., Crestani, Juliana, Fabrizio, Michele, Fiorentino, Giuliana, Gilligan, Christina K., Monelli, Matteo, Stetson, Peter B.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 14.05.2021; IOP; IOP Publishing; American Astronomical Society
• Subjects: Astrophysics; Calibration; Datasets; Globular clusters; Globular star clusters; Infrared photometry; Infrared radiation; Infrared telescopes; James Webb Space Telescope; Light curve; Metallicity; Parameters; Photometry; Physics; Pulsating variable stars; RR Lyrae variable stars; RRab variable stars; Scattering; Space telescopes; Spectroscopy
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/abefd4

NRC publication: Yes
We present newly calibrated period–ϕ31–[Fe/H] relations for fundamental-mode RR Lyrae stars in the optical and, for the first time, mid-infrared. This work's calibration data set provides the largest and most comprehensive span of parameter space to date, with homogeneous metallicities from −3 ≲ [Fe/H] ≲ 0.4 and accurate Fourier parameters derived from 1980 ASAS-SN (V band) and 1083 WISE (NEOWISE extension, W1 and W2 bands) RR Lyrae stars with well-sampled light curves. We compare our optical period–ϕ31–[Fe/H] relation with those available in the literature and demonstrate that our relation minimizes systematic trends in the lower and higher metallicity range. Moreover, a direct comparison shows that our optical photometric metallicities are consistent with both those from high-resolution spectroscopy and globular clusters, supporting the good performance of our relation. We found an intrinsic scatter in the photometric metallicities (0.41 dex in the V band and 0.50 dex in the infrared) by utilizing large calibration data sets covering a broad metallicity range. This scatter becomes smaller when optical and infrared bands are used together (0.37 dex). Overall, the relations derived in this work have many potential applications, including large-area photometric surveys with James Webb Space Telescope in the infrared and LSST in the optical.