The VMC Survey. XI. Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae

Abstract

We present a deep near-infrared color--magnitude diagram of the Galactic globular cluster 47 Tucanae, obtained with the Visible and Infrared Survey Telescope for Astronomy (VISTA) as part of the VISTA near-infrared Y, J, K_s survey of the Magellanic System (VMC). The cluster stars comprising both the subgiant and red-giant branches exhibit apparent, continuous variations in color--magnitude space as a function of radius. Subgiant-branch stars at larger radii are systematically brighter than their counterparts closer to the cluster core; similarly, red-giant-branch stars in the cluster's periphery are bluer than their more centrally located cousins. The observations can very well be described by adopting an age spread of ~0.5 Gyr as well as radial gradients in both the cluster's helium abundance (Y) and metallicity (Z), which change gradually from Y = 0.28, Z = 0.005 in the cluster core to Y = 0.25, Z = 0.003 in its periphery. We conclude that the cluster's inner regions host a significant fraction of second-generation stars, which decreases with increasing radius; the stellar population in the 47 Tuc periphery is well approximated by a simple stellar population.

40 pages, 20 figures, accepted for publication in ApJ

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Cited by in corpus (11)

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• AGB Sodium Abundances in the Globular Cluster 47 Tucanae (NGC 104)
• The VMC survey - XV. The Small Magellanic Cloud--Bridge connection history as traced by their star cluster populations
• Stellar loci I. Metallicity dependence and intrinsic widths
• The dynamical origin of multiple populations in intermediate-age clusters in the Magellanic Clouds
• The VMC survey -- XXXIX: Mapping metallicity trends in the Small Magellanic Cloud using near-infrared passbands
• The radial distributions of the two main-sequence components in the young massive star cluster NGC 1856
• Stellar populations in star clusters
• The VMC survey -- LIII. Data release #7. Complete survey data and data from additional programmes
• The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS) II: Characterization of 47 Tuc with Bayesian Statistics
• The Origin of Young Stellar Populations in NGC 1783: Accretion of External Stars