Program: GS-2007B-Q-29

We propose to determine the age, metallicity and [alpha/Fe] abundance gradients in the spheroids and discs of a sample of 12 edge-on S0 galaxies using ultra-deep long-slit spectroscopy with GMOS. We will combine this data with i-band imaging to allow a separation of the relative luminosity contributions of both components. We have previously used this approach to demonstrate that the field S0 galaxy NGC 3115 contains a stellar disc that differs significantly from the spheroid of the galaxy in age (6Gyrs vs 12 Gyrs), metallicity (z~0.2 vs z~ -0.2) and [alpha/Fe] abundance (0.17 vs 0.3). This study which extends our successful programmes from 06B and 07A will determine the epoch at which star formation ended in both components for S0s across the full range of luminosity, bulge-to-disc ratio and environment. Our results will be compared to the predictions of heirarchical models of galaxy formation.