NGC752 abundances from IR spectra

High-excitation CI lines present in both near-infrared and optical spectra were also included in the C abundance determinations. Carbon isotopic ratios were derived from the R-branch band heads of first overtone (2-0) and (3-1) ^12^CO and (2-0) ^13^CO lines near 23440{AA} and (3-1) ^13^CO lines at about 23730{AA}. The CNO abundances and ^12^C/^13^C ratios are all consistent with our giants having completed 'first dredge-up' envelope mixing of CN-cycle products.

We independently assessed NGC752 stellar membership from Gaia astrometry, leading to a new colour-magnitude diagram for this cluster. Applications of Victoria isochrones and MESA models to these data yield an updated NGC752 cluster age (1.52Gyr) and evolutionary stage indications for the programme stars. The photometric evidence and spectroscopic light element abundances all suggest that the most, perhaps all of the programme stars are members of the helium-burning red clump in this cluster.