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High-resolution infrared spectra of NGC 6342 and 6528: two moderately reddened bulge globular clusters
Authors:L Origlia  E Valenti  R M Rich
Institution:INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna, Italy;Dipartimento Astronomia, Universitàdi Bologna, Via Ranzani 1, I-40127 Bologna, Italy;Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1562, USA
Abstract:Using the Near Infrared Spectrometer (NIRSPEC) spectrograph at Keck II, we have obtained infrared (IR) echelle spectra covering the range  1.5 –1.8 μm  for the moderately reddened bulge globular clusters NGC 6342 and 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 favouring the scenario of a rapid bulge formation and chemical enrichment. We also measure very low 12C/13C isotopic ratios (≈5 in NGC 6342 and ≈8 in NGC 6528), suggesting that extra-mixing mechanisms resulting from cool bottom processing are at work during evolution along the red giant branch (RGB).
Keywords:techniques: spectroscopic  stars: abundances  stars: late-type  Galaxy: bulge  globular clusters: individual: NGC 6342  globular clusters: individual: NGC 6528
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