Near-Infrared Photometry of Globular Clusters Towards the Galactic Bulge: Observations and Photometric Metallicity Indicators

Abstract

We present wide field JHKs photometry of 16 Galactic globular clusters located towards the Galactic bulge, calibrated on the 2MASS photometric system. Differential reddening corrections and statistical field star decontamination are employed for all of these clusters before fitting fiducial sequences to the cluster red giant branches (RGBs). Observed values and uncertainties are reported for several photometric features, including the magnitude of the RGB bump, tip, the horizontal branch (HB) and the slope of the upper RGB. The latest spectroscopically determined chemical abundances are used to build distance- and reddening-independent relations between observed photometric features and cluster metallicity, optimizing the sample size and metallicity baseline of these relations by supplementing our sample with results from the literature. We find that the magnitude different between the HB and the RGB bump can be used to predict metallicities, in terms of both iron abundance [Fe/H] and global metallicity [M/H], with a precision of better than 0.1 dex in all three near-IR bandpasses for relative metal-rich ([M/H]$\gtrsim$-1) clusters. Meanwhile, both the slope of the upper RGB and the magnitude difference between the RGB tip and bump are useful metallicity indicators over the entire sampled metallicity range (-2$\lesssim$[M/H]$\lesssim$0) with a precision of 0.2 dex or better, despite model predictions that the RGB slope may become unreliable at high (near-solar) metallicities. Our results agree with previous calibrations in light of the relevant uncertainties, and we discuss implications for clusters with controversial metallicities as well as directions for further investigation.

MNRAS, in press, 31 pages, 16 figures, 9 tables. A supplementary figure set including color-magnitude diagrams and luminosity functions will be available online upon publication

References in corpus (24)

• The Dartmouth Stellar Evolution Database
• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• Tip of the Red Giant Branch Distances. I. Optimization of a Maximum Likelihood Algorithm
• Open clusters in dense fields: the importance of field-star decontamination for NGC5715, Lynga4, Lynga9, Trumpler23, Trumpler26 and Czernik37
• Isochrones for Old (> 5 Gyr) Stars and Stellar Populations. I. Models for $-2.4\le$ [Fe/H] $\le +0.6$, $0.25\le Y\le 0.33$, and $-0.4\le$ [$\alpha$\Fe] $\le +0.4$
• The period-luminosity relation for type II Cepheids in globular clusters
• Manganese Abundances in Cluster and Field Stars
• High-resolution abundance analysis of red giants in the globular cluster NGC 6522
• High resolution infrared spectra of NGC 6440 and NGC 6441: two massive Bulge Globular Clusters
• High resolution reddening map in the direction of the stellar system Terzan 5
• VLT-UVES abundance analysis of four giants in NGC 6553
• Extinction Maps towards the Milky Way Bulge: 2D and 3D Tests with APOGEE
• Near-infrared observations of the Fornax dwarf galaxy. I. The red giant branch
• High-precision astrometry with VVV. I. An independent reduction pipeline for VIRCAM@VISTA
• FORS2/VLT survey of Milky Way globular clusters I. Description of the method for derivation of metal abundances in the optical and application to NGC 6528, NGC 6553, M 71, NGC 6558, NGC 6426 and Terzan 8
• Mass Outflow and Chromospheric Activity of Red Giant Stars in Globular Clusters II. M13 and M92
• Searching for variable stars in the cores of five metal rich globular clusters using EMCCD observations
• NGC 6522: A typical globular cluster in the Galactic bulge without signatures of rapidly rotating Population III stars
• High-resolution CRIRES spectra of Terzan1: a metal-poor globular cluster toward the inner bulge
• The VVV-SkZ pipeline: an automatic PSF-fitting photometric pipeline for the VVV survey
• Variable Stars in Metal-Rich Globular Clusters. IV. Long Period Variables in NGC 6496
• A Chemical Abundance Study of three RHB and two RGB stars in NGC6637 (M69)

Cited by in corpus (20)

• A Deep View of a Fossil Relic in the Galactic Bulge: The Globular Cluster HP1
• Population synthesis of helium white dwarf--red giant star mergers and the formation of lithium-rich giants and carbon stars
• A Census of Blue Stragglers in Gaia DR2 Open Clusters as a Test of Population Synthesis and Mass Transfer Physics
• A panchromatic view of the bulge globular cluster NGC 6569
• CAPOS: The bulge Cluster APOgee Survey I. Overview and initial ASPCAP results
• Three candidate globular clusters discovered in the Galactic bulge
• Absolute Properties of the Pulsating Post-mass Transfer Eclipsing Binary OO Draconis
• The vertical Na-O relation in the bulge globular cluster NGC 6553
• Discovery of a new nearby globular cluster with extreme kinematics located in the extension of a halo stream
• Extremely low-mass white dwarf stars observed in Gaia DR2 and LAMOST DR8
• The Pre-He White Dwarfs in Eclipsing Binaries. I. WASP 0131+28
• Isochrone fitting of Galactic globular clusters -- II. NGC6205 (M13)
• A long-period pre-ELM system discovered from LAMOST medium-resolution survey
• An Intriguing Globular Cluster in the Galactic Bulge from the VVV Survey
• Compact Objects in close orbits as Gravitational Wave Sources: Formation Scenarios and Properties
• Chemical analysis of the Bulge Globular Cluster NGC 6553
• Infrared photometry and CaT spectroscopy of globular cluster M 28 (NGC 6626)
• KIC 12268220: A $\delta$ Scuti Pulsating Star and an Active Protohelium White Dwarf in an Eclipsing Binary System
• The double helium-white dwarf channel for the formation of AM CVn binaries
• Pulsation and Rotation of the EL CVn-type Eclipsing Binary 1SWASP J024743.37-251549.2