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Near-Infrared photometry and spectroscopy of NGC 6539 and UKS 1: two intermediate metallicity Bulge Globular Clusters

L. Origlia·E. Valenti·R. M. Rich·F. R. Ferraro
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Abstract

Using the SofI imager at ESO/NTT and NIRSPEC spectrograph at KeckII, we have obtained J,K images and echelle spectra covering the range 1.5 - 1.8 micron for the intermediate metallicity Bulge globular clusters NGC6539 and UKS1. We find [Fe/H]=-0.76 and -0.78, respectively, and an average alpha-enhancement of +0.44 dex and +0.31 dex, consistent with previous measurements of metal rich Bulge clusters, and favoring the scenario of rapid chemical enrichment. We also measure very low 12C/13C=4.5 +/-1 isotopic ratios in both clusters, suggesting that extra-mixing mechanisms due to cool bottom processing are at work during the evolution along the Red Giant Branch. Finally, we measure accurate radial velocities of =+31 +/-4Km/s and =+57 +/-6Km/s and velocity dispersion of about 8 Km/s and 11 Km/s for NGC6539 and UKS1, respectively.

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L. Origlia, E. Valenti, R. M. Rich, F. R. Ferraro. 2005-08-05. Near-Infrared photometry and spectroscopy of NGC 6539 and UKS 1: two intermediate metallicity Bulge Globular Clusters. https://doi.org/10.1111/j.1365-2966.2005.09490.x

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