We present spectroscopy for globular clusters ( GCs ) in the elliptical galaxy NGC 4365 , obtained with the LRIS spectrograph on the Keck I telescope .
Previous studies have shown that the optical color distribution of GCs in NGC 4365 lacks the bimodal structure that is common in globular cluster systems , showing only a single broad peak .
Measurements of Balmer line indices ( H \beta , H \gamma and H \delta ) on the GC spectra support recent suggestions by Puzia et al. , based on optical and near-infrared photometry , that some of the clusters in NGC 4365 are intermediate-age ( 2–5 Gyrs ) and metal-rich ( -0.4 \lesssim \mbox { [ $Z$ / H ] } \lesssim 0 ) rather than old ( \sim 10–15 Gyrs ) and metal-poor .
We also find some genuinely metal-poor , old clusters , suggesting that the ages and metallicities of the two populations conspire to produce the single broad distribution observed in optical colors .