Published online by Cambridge University Press: 09 March 2010
1. McWilliam and Zoccali (2009) show the existence of two Red Clump populations towards the Galactic bulge, based on 2MASS data. 2.Measured [Mg/Fe], [Al/Fe], and [La/Eu] ratios in the bulge are consistent with a rapid formation timescale (<1Gyr), which also requires a slightly top-heavy IMF to reproduce the mean bulge metallicity. The [C/O] and [O/Fe] ratios are consistent if their predicted metal-dependent yields from massive stars with winds are considered. The decline in explosive [α/Fe] (Si, Ca, and Ti) can only be understood if their yields also decline with metallicity above [Fe/H]~−1.