ORCID Profile
0000-0001-6802-6539
Current Organisation
University of Delhi
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Publisher: American Astronomical Society
Date: 02-2023
Abstract: RR Lyrae variables are excellent Population II distance indicators thanks to their well-defined period–luminosity relations (PLRs) at infrared wavelengths. We present results of near-infrared (NIR) monitoring of Galactic globular clusters to empirically quantify the metallicity dependence of NIR PLRs for RR Lyrae variables. Our s le includes homogeneous, accurate, and precise photometric data for 964 RR Lyrae variables in 11 globular clusters covering a large metallicity range (Δ[Fe/H] ∼ 2 dex). We derive JHK s -band period–luminosity–metallicity (PLZ) and period–Wesenheit–metallicity (PWZ) relations anchored using 346 Milky Way field RR Lyrae stars with Gaia parallaxes, and simultaneously solved for independent distances to globular clusters. We find a significant metallicity dependence of ∼0.2 mag dex −1 in the JHK s -band PLZ and PWZ relations for RR Lyrae stars independent of the adopted metallicity scale. The metallicity coefficients and the zero-points of the empirical PLZ and PWZ relations are in excellent agreement with the predictions from the horizontal branch evolution and pulsation models. Furthermore, RR Lyrae–based distances to our s le of globular clusters are also statistically consistent with other independent measurements in the literature. Our recommended empirical JHK s -band PLZ relations for RR Lyrae stars with periods of fundamental mode pulsation ( P f ) are: M J = − 0.44 ( ± 0.03 ) − 1.83 ( ± 0.02 ) log ( P f ) + 0.20 ( ± 0.02 ) [ Fe / H ] ( σ = 0.05 mag ) M H = − 0.74 ( ± 0.02 ) − 2.29 ( ± 0.02 ) log ( P f ) + 0.19 ( ± 0.01 ) [ Fe / H ] ( σ = 0.05 mag ) M K s = − 0.80 ( ± 0.02 ) − 2.37 ( ± 0.02 ) log ( P f ) + 0.18 ( ± 0.01 ) [ Fe / H ] ( σ = 0.05 mag ) .
Publisher: American Astronomical Society
Date: 27-10-2020
Publisher: American Astronomical Society
Date: 03-2021
Abstract: We present new near-infrared, JHK s , period–luminosity relations (PLRs) for RR Lyrae variables in the Messier 53 (M53 or NGC 5024) globular cluster. Multi-epoch JHK s observations, obtained with the WIRCam instrument on the 3.6 m Canada–France–Hawaii Telescope, are used for the first time to estimate precise mean magnitudes for 63 RR Lyrae stars in M53 including 29 fundamental-mode (RRab) and 34 first-overtone mode (RRc) variables. The JHK s -band PLRs for RR Lyrae stars are best constrained for RRab types with a minimal scatter of 22, 23, and 19 mmag, respectively. The combined s le of RR Lyrae is used to derive the K s -band PLR, K s = − 2.303 ( 0.063 ) log P + 15.212 ( 0.016 ) , exhibiting a 1 σ dispersion of only 0.027 mag. Theoretical period–luminosity–metallicity (PLZ) relations are used to predict parallaxes for 400 Galactic RR Lyrae, resulting in a median parallax zero-point offset of −7 ± 3 μ as in Gaia Early Data Release 3 (EDR3), which increases to 22 ± 2 μ as if the parallax corrections are applied. We also estimate a robust distance modulus, μ M53 = 16.403 ± 0.024 (statistical) ± 0.033 (systematic) mag, to M53 based on theoretical calibrations. Homogeneous and precise mean magnitudes for RR Lyrae in M53 together with similar literature data for M3, M4, M5, and ω Cen are used to empirically calibrate a new RR Lyrae PLZ K s relation, K s = − 0.848 ( 0.007 ) − 2.320 ( 0.006 ) log P + 0.166 ( 0.011 ) [ Fe / H ] , anchored with Gaia EDR3 distances and theoretically predicted relations, and to simultaneously estimate precise RR Lyrae-based distances to these globular clusters.
Publisher: American Astronomical Society
Date: 08-10-2019
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for HARINDER SINGH.