| dc.identifier.citation | Chengyan , L , de Grijs , R , Deng , L , Rubele , S , Wang , C , Bekki , K , Cioni , M-RL , Clementini , G , Emerson , J P , For , B-Q , Girardi , L , Groenewegen , M A T , Guandalini , R , Gullieuszik , M , Marconi , M , Piatti , A , Ripepi , V & van Loon , J T 2014 , ' The VMC survey - XI : Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae ' , The Astrophysical Journal , vol. 790 , no. 1 , 35 . https://doi.org/10.1088/0004-637X/790/1/35 | |
| dc.description.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, 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. | en |
