Old Globular Clusters Masquerading as Young in NGC 4365?

High signal-to-noise, low-resolution spectra have been obtained for 22globular clusters (GCs) in NGC 4365. Some of these were selected as probablerepresentatives of an intermediate-age (2-5 Gyr), extremely metal-rich GCsubpopulation. The presence of such a subpopulation had been inferred from theunusual optical and near-IR color distributions of GCs in this otherwisetypical Virgo elliptical galaxy. However, ages derived from Lick indices areconsistent with uniformly old mean ages for all GCs in our sample. Themetallicities of the clusters show some evidence for a trimodal distribution.The most metal-poor and metal-rich peaks are consistent with the valuesexpected for an elliptical galaxy of this luminosity, but there appears to bean additional, intermediate-metallicity peak lying between them. New HubbleSpace Telescope photometry is consistent with this result. A plausible scenariois that in earlier data these three peaks merged into a single broaddistribution. Our results suggest that it is difficult to identifyintermediate-age GC subpopulations solely with photometry, even when bothoptical and near-infrared colors are used.Comment: 30 pages, including 11 figures. AJ in pres