Stellar populations of globular clusters in the elliptical galaxy NGC 1407

We present high-quality Keck spectroscopic data for a sample of 20 globular clusters (GCs) in the massive E0 galaxy NGC 1407. A subset of 20 line-strength indices of the Lick/IDS systemhas been measured for both the GC system and the central integrated starlight of the galaxy. Ages, metallicities, and [alpha/Fe] ratios have been derived using several different approaches. The majority of GCs in NGC 1407 studied are old, follow a tight metallicity sequence reaching values slightly above solar, and exhibit mean [alpha/Fe] ratios of similar to 0.3 dex. In addition, three GCs are formally derived to be young (similar to 4Gyr), but we argue that they are actually old GCs hosting blue horizontal branches. We report, for the first time, evidence for the existence of two chemically distinct subpopulations of metal-rich (MR) GCs. We find that some MR GCs exhibit significantly larger [Mg/Fe] and [C/Fe] ratios. Different star formation timescales are proposed to explain the correlation between Mg and C abundances. We also find striking CN overabundances over the entire GC metallicity range. It is interesting to note that the behavior of C and N in metal-poor GCs clearly deviates from that in MRGCs. In particular, forMRGCs, Nincreases dramatically while C essentially saturates. This may be interpreted as a consequence of the increasing importance of the CNO cycle with increasing metallicity.