New near-infrared JHK_s light-curve templates for RR Lyrae variables^⋆

¹ Instituto Milenio de Astrofísica, Santiago, Chile
e-mail: vittorio.braga@roma2.infn.it
² Departamento de Física, Facultad de Ciencias Exactas, Universidad Andrés Bello, Fernández Concha 700, Las Condes, Santiago, Chile
³ Herzberg Astronomy and Astrophysics, National Research Council, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7, Canada
⁴ Department of Physics, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
⁵ INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
⁶ INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
⁷ INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
⁸ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁹ INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
¹⁰ Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
¹¹ Department of Physics, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA
¹² The Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA
¹³ INAF-Osservatorio Astronomico d’Abruzzo, Via Mentore Maggini snc, Loc. Collurania, 64100 Teramo, Italy
¹⁴ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹⁵ Pontificia Universidad Catolica de Chile, Instituto de Astrofisica, Av. Vicuña Mackenna 4860, Santiago, Chile
¹⁶ Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA
¹⁷ Space Science Data Center, Via del Politecnico snc, 00133 Roma, Italy
¹⁸ Department of Astronomy & Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
¹⁹ Department of Astronomy, Columbia University, 550 W 120th st., New York, NY 10027, USA
²⁰ Sterrewacht Leiden, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
²¹ Department of Astronomy, University of Michigan, Ann Arbor, MI, USA
²² Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
²³ Vatican Observatory, 00120 Vatican City, Italy
²⁴ Instituto de Astrofísica de Canarias, Calle Via Lactea s/n, 38205 La Laguna, Tenerife, Spain
²⁵ INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
²⁶ Department of Astronomy and McDonald Observatory, The University of Texas, Austin, TX 78712, USA
²⁷ Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
²⁸ Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile
²⁹ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Munchen, Germany

Received: 15 December 2018
Accepted: 30 January 2019

Abstract

We provide homogeneous optical (UBVRI) and near-infrared (NIR, JHK) time series photometry for 254 cluster (ω Cen, M 4) and field RR Lyrae (RRL) variables. We ended up with more than 551 000 measurements, of which only 9% are literature data. For 94 fundamental (RRab) and 51 first overtones (RRc) we provide a complete optical/NIR characterization (mean magnitudes, luminosity amplitudes, epoch of the anchor point). The NIR light curves of these variables were adopted to provide new light-curve templates for both RRc and RRab variables. The templates for the J and the H bands are newly introduced, together with the use of the pulsation period to discriminate among the different RRab templates. To overcome subtle uncertainties in the fit of secondary features of the light curves we provide two independent sets of analytical functions (Fourier and periodic Gaussian series). The new templates were validated by using 26 ω Cen and Bulge RRLs. We find that the difference between the measured mean magnitude along the light curve and the mean magnitude estimated by using the template on a single randomly extracted phase point is better than 0.01 mag (σ = 0.04 mag). We also validated the template on variables for which at least three phase points were available, but without information on the phase of the anchor point. We find that the accuracy of the mean magnitudes is also ∼0.01 mag (σ = 0.04 mag). The new templates were applied to the Large Magellanic Cloud (LMC) globular cluster Reticulum and by using literature data and predicted PLZ relations we find true distance moduli μ = 18.47 ± 0.10 (rand.) ± 0.03 (syst.) mag (J) and 18.49 ± 0.09 ± 0.05 mag (K). We also used literature optical and mid-infrared data and we found a mean μ of 18.47 ± 0.02 ± 0.06 mag, suggesting that Reticulum is ∼1 kpc closer than the LMC.