C and N abundances in globular clusters : I. the case of 47 Tuc (NGC 104) and the effect of the first dredge-up: Implications for the isochrone fitting
Context. Globular clusters exhibit star-to-star chemical variations that are traceable through both photometric and spectroscopic data. While UV photometry and light-elements such as Na and O are commonly used for this purpose, the optical V versus (V-I) color magnitude diagram (CMD) is often assumed to be relatively unaffected by such inhomogeneities and is used to derive basic cluster parameters
