The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS) I: A Pilot Study of the stellar populations in NGC 2298 and NGC 3201

Abstract

We present the first results from the GeMS/GSAOI Galactic Globular Cluster Survey (G4CS) of the Milky-Way globular clusters (GCs) NGC 3201 and NGC 2298. Using the Gemini South Adaptive Optics Imager (GSAOI), in tandem with the Gemini Multi-conjugate adaptive optics System (GeMS) on the 8.1-meter Gemini-South telescope, we collected deep near-IR observations of both clusters, resolving their constituent stellar populations down to $K_s\simeq 21$ Vega mag. Point spread function (PSF) photometry was performed on the data using spatially-variable PSFs to generate $JH{K}_s$ photometric catalogues for both clusters. These catalogues were combined with Hubble Space Telescope (HST) data to augment the photometric wavelength coverage, yielding catalogues that span the near-ultraviolet (UV) to near-infrared (near-IR). We then applied 0.14 mas/year accurate proper-motion cleaning, differential-reddening corrections and chose to anchor our isochrones using the lower main-sequence knee (MSK) and the main-sequence turn-off (MSTO) prior to age determination. As a result of the data quality, we found that the $K_s$ vs. F606W$-K_s$ and F336W vs. F336W$-K_s$ color-magnitude diagrams (CMDs) were the most diagnostically powerful. We used these two color combinations to derive the stellar-population ages, distances and reddening values for both clusters. Following isochrone-fitting using three different isochrone sets, we derived best-fit absolute ages of $12.2\pm 0.5$ Gyr and $13.2\pm 0.4$ Gyr for NGC 3201 and NGC 2298, respectively. This was done using a weighted average over the two aforementioned color combinations, following a pseudo-${\chi }^2$ determination of the best-fit isochrone set. Our derived parameters are in good agreement with recent age determinations of the two clusters, with our constraints on the ages being or ranking among the most statistically robust.

Accepted for publication in The Astrophysical Journal

References in corpus (23)

• The NumPy array: a structure for efficient numerical computation
• The Dartmouth Stellar Evolution Database
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• 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
• The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• The stellar halo of the Galaxy
• Paving the way for the JWST: witnessing globular cluster formation at z>3
• Scientific Discovery with the James Webb Space Telescope
• 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] $\le +0.4$
• MCAO near-IR photometry of the Globular Cluster NGC 6388: MAD observations in crowded fields
• Astrometric performance of the Gemini multi-conjugate adaptive optics system in crowded fields
• The ACS Survey of Galactic Globular Clusters XIV: Bayesian Single-Population Analysis of 69 Globular Clusters
• Relative distances of Omega Centauri and 47 Tucanae
• Ultra-deep GEMINI near-infrared observations of the bulge globular cluster NGC 6624
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. VIII. Preliminary Public Catalog Release
• GeMS/GSAOI photometric and astrometric performance in dense stellar fields
• Blue Straggler Star Populations in Globular Clusters: II. Proper-Motion Cleaned HST Catalogs of BSSs in 38 Galactic GCs
• Bayesian Analysis of Two Stellar Populations in Galactic Globular Clusters III: Analysis of 30 Clusters
• Gemini Frontier Fields: Wide-field Adaptive Optics $K_s$-band Imaging of the Galaxy Clusters MACS J0416.1-2403 and Abell 2744
• Probing the nuclear star cluster of galaxies with ELTs
• On the use of the main sequence knee (saddle) to measure globular cluster ages

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