CN variations among asymptotic giant branch and horizontal branch stars in the intermediate metallicity globular clusters M5, M4, and NGC 6752

An investigation is conducted of the 3883-A CN band strengths among stars in the asymptotic giant branch evolutionary phase in the M5 and NGC 6752 globular clusters. It is suggested that the differences in CN distributions among the evolved stars in these clusters may be a consequence of the varying degrees of C-to-N processing to which they were subjected in the preceding, red giant phase of evolution.