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High resolution infrared spectra of bulge globular clusters: Liller~1 and NGC 6553

Livia Origlia·R. Michael Rich·Sandra Castro
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Abstract

Using the NIRSPEC spectrograph at Keck II, we have obtained echelle spectra covering the range 1.5-1.8um for 2 of the brightest giants in Liller 1 and NGC 6553, old metal rich globular clusters in the Galactic bulge. We use spectrum synthesis for the abundance analysis, and find [Fe/H]=-0.3 +/- 0.2 and [O/H]=+0.3 +/- 0.2 dex. The composition of the clusters is similar to that of field stars in the bulge and is consistent with a sceanrio in which the clusters formed early, with rapid enrichment. We have dificulty achieveing a good fit to the spectrum of NGC 6553 using either the low or the high values recently reported in the literature, unless unusually large, or no alpha-element enhancements are adopted, respectively.

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Livia Origlia, R. Michael Rich, Sandra Castro. 2001-12-05. High resolution infrared spectra of bulge globular clusters: Liller~1 and NGC 6553. https://doi.org/10.1086/338897

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