The VMC survey - XI : Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae

Chengyan, Li, de Grijs, R., Deng, Licai, Rubele, S., Wang, Chuchu, Bekki, K., Cioni, M-R.L., Clementini, G., Emerson, J.P., For, Bi-Qing, Girardi, L., Groenewegen, M.A.T., Guandalini, Roald, Gullieuszik, M., Marconi, M., Piatti, Andres, Ripepi, V. and van Loon, J. Th. (2014) The VMC survey - XI : Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae. The Astrophysical Journal, 790 (1): 35. ISSN 0004-637X
Copy

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, Ks 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.


picture_as_pdf
906904.pdf
subject
Submitted Version

View Download

Atom BibTeX OpenURL ContextObject in Span OpenURL ContextObject Dublin Core MPEG-21 DIDL Data Cite XML EndNote HTML Citation METS MODS RIOXX2 XML Reference Manager Refer ASCII Citation
Export

Downloads