Program: GS-2007A-Q-63

We propose to examine 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 in age (6 Gyrs vs. 12 Gyrs), metallicity (z~0.2 vs. z ~-0.2) and [alpha/Fe] abundance (0.17 vs. 0.3) from the bulge of the galaxy. This study which builds on our pilot programme from 06B will allow us to 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 then be compared to the predictions of hierarchical models of galaxy formation.