2010AJ....139.2034A

High-dispersion spectra of 89 potential members of the old, super-metal-rich open cluster, NGC 6253, have been obtained with the HYDRA multi-object spectrograph. Based upon radial-velocity measurements alone, 47 stars at the turnoff of the cluster color-magnitude diagram (CMD) and 18 giants are identified as potential members. Five turnoff stars exhibit evidence of binarity while proper-motion data eliminate two of the dwarfs as members. The mean cluster radial velocity from probable single-star members is -29.4±1.3 km/s (sd). A discussion of the current estimates for the cluster reddening, derived independently of potential issues with the BV cluster photometry, lead to an adopted reddening of E(B - V) = 0.22±0.04. From equivalent width analyses of 38 probable single-star members near the CMD turnoff, the weighted average abundances are found to be [Fe/H] = +0.43±0.01, [Ni/H] = +0.53±0.02, and [Si/H] = +0.43^0.03_0.04, where the errors refer to the standard errors of the weighted mean. Weak evidence is found for a possible decline in metallicity with increasing luminosity among stars at the turnoff. We discuss the possibility that our turnoff stars have been affected by microscopic diffusion. For 15 probable single-star members among the giants, spectrum synthesis leads to abundances of +0.46^0.02_0.03 for [Fe/H]. While NGC 6253 is less than half the age of NGC 6791, it is at least as metal-rich and, within the uncertainties, exhibits the same general abundance pattern as that typified by super-metal-rich dwarfs of the galactic bulge.