The VMC survey. XI. Radial stellar population gradients in the galactic globular cluster 47 Tucanae
- Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China)
- Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China)
- INAF-Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, I-35122 Padova (Italy)
- Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China)
- ICRAR M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)
- Department of Physics, Astronomy, and Mathematics, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
- INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
- Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)
- Royal Observatory of Belgium, Ringlaan 3, 1180 Ukkel (Belgium)
- Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D 2401, 3001 Leuven (Belgium)
- INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, I-80131 Naples (Italy)
- Observatorio Astrońomico, Universidad Nacional de Córdoba, Laprida 854, 5000 Córdoba (Argentina)
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{sub 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.
- OSTI ID:
- 22365608
- Journal Information:
- Astrophysical Journal, Vol. 790, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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