The anticorrelation of cyanogen and CH on the giant branch of 47 Tucanae

CN and G band measurements are presented for 112 stars on the red giant and asymptotic giant branches of 47 Tucanae. The data support the hypothesis (at the 0.00002 significance level) that there is an anticorrelation between CN and CH on the red giant branch (RGB) as has been previously reported for the horizontal-branch stars in this cluster. There seems little need to invoke the occurrence of mixing phenomena during the transition of a star from Mv of about 0.0 on the RGB to the horizontal branch and later evolutionary phases, as has been suggested for the more metal-poor clusters such as M92. The finding of Bell, Hesser, and Cannon (1983) that there appears to be an anticorrelation of CN and CH in their best observed CN-strong, CN-weak pair of stars at the turnoff of this cluster is highlighted. It is emphasized, however, that no primordial scenario has yet been devised which can explain the details of the carbon nitrogen anticorrelation implied by these data.