High resolution infrared spectra of NGC 6342 and NGC 6528 : two moderately reddened Bulge Globular Clusters ⋆
نویسندگان
چکیده
Using the NIRSPEC spectrograph at Keck II, we have obtained infrared echelle spectra covering the range 1.5− 1.8 μm for the moderately reddened bulge globular clusters NGC 6342 and NGC 6528, finding [Fe/H]=–0.60 and –0.17 dex, respectively. We measure an average α-enhancement of ≈ +0.33 dex in both clusters, consistent with previous measurements on other metal rich bulge clusters, and favoring the scenario of a rapid bulge formation and chemical enrichment. We also measure very low C/C isotopic ratios (≈5 in NGC 6342 and ≈8 in NGC 6528), suggesting that extra-mixing mechanisms due to cool bottom processing are at work during evolution along the Red Giant Branch.
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