Old open clusters as key tracers of Galactic chemical evolution. I. Fe\n abundances in NGC 2660, NGC 3960, and Berkeley 32

Abstract

We obtained high-resolution UVES/FLAMES observations of a sample of nine old\nopen clusters spanning a wide range of ages and Galactocentric radii. The goal\nof the project is to investigate the radial metallicity gradient in the disk,\nas well as the abundance of key elements (alpha and Fe-peak elements). In this\npaper we present the results for the metallicity of three clusters: NGC 2660\n(age ~1 Gyr, Galactocentric distance of 8.68 kpc), NGC 3960 (~ 1 Gyr, 7.80\nkpc), and Be 32 (~6-7 Gyr, 11.30 kpc). For Be 32 and NGC 2660, our study\nprovides the first metallicity determination based on high-resolution spectra.\nWe performed equivalent width analysis with the spectral code MOOG, which\nallows us to define a metallicity scale and build a homogeneous sample. We find\nthat NGC 3960 and NGC 2660 have a metallicity that is very close to solar\n([Fe/H]=+0.02 and +0.04, respectively), while the older Be 32 turns out to have\n[Fe/H]=$-$0.29.\n