High-resolution infrared spectra of NGC 6342 and 6528: two moderately reddened bulge globular clusters

Using the Near Infrared Spectrometer (NIRSPEC) spectrograph at Keck II, we have obtained infrared (IR) echelle spectra covering the range 1.5-1.8 mum for the moderately reddened bulge globular clusters NGC6342 and 6528, finding [Fe/H] = -0.60 and -0.17 dex, respectively. We measure an average alpha-enhancement of approximate to+0.33 dex in both clusters, consistent with previous measurements on other metal-rich bulge clusters, and favouring the scenario of a rapid bulge formation and chemical enrichment. We also measure very low C-12/C-13 isotopic ratios (approximate to5 in NGC 6342 and approximate to8 in NGC 6528), suggesting that extra-mixing mechanisms resulting from cool bottom processing are at work during evolution along the red giant branch (RGB).