Stellar Populations of Globular Clusters in the Elliptical Galaxy NGC 1407

We present high-quality, Keck spectroscopic data for a sample of 20 globularclusters (GCs) in the massive E0 galaxy NGC1407. A subset of twentyline-strength indices of the Lick/IDS system have been measured for both the GCsystem and the central integrated star-light of the galaxy. Ages, metallicitiesand [alpha/Fe] ratios have been derived using several different approaches. Themajority GCs in NGC1407 studied are old, follow a tight metallicity sequencereaching values slightly above solar, and exhibit mean [alpha/Fe] ratios of ~0.3 dex. In addition, three GCs are formally derived to be young (~ 4 Gyr), butwe argue that they are actually old GCs hosting blue horizontal branches. Wereport, for the first time, evidence for the existence of twochemically-distinct subpopulations of metal-rich (MR) GCs. We find some MR GCsexhibit significantly larger [Mg/Fe] and [C/Fe] ratios. Different starformation time-scales are proposed to explain the correlation between Mg and Cabundances. We also find striking CN overabundances over the entire GCmetallicity range. Interestingly, the behavior of C and N in metal-poor (MP)GCs clearly deviates from the one in MR GCs. In particular, for MR GCs, Nincreases dramatically while C essentially saturates. This may be interpretedas a consequence of the increasing importance of the CNO cycle with increasingmetallicity.Comment: 53 pages, 11 figures, 5 tables. Accepted for publication in The Astronomical Journa