Metallicities, Relative Ages, and Kinematics of Stellar Populations in ω Centauri

Abstract

We present results of an extensive spectroscopic survey of subgiant stars in the stellar system omega Cen. Using infrared Ca II triplet lines, we derived metallicities and radial velocities for more than 250 stars belonging to different stellar populations of the system. We find that the most metal-rich component, the anomalous subgiant branch (SGB-a), has a metallicity of [Fe/H]~-0.6, fully compatible with that determined along the anomalous red giant branch (RGB-a). Our analysis suggests that the age of this component and of the other metal-intermediate (-1.4