An infrared spectroscopic study of eight Galactic globular clusters
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Date
2004
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Abstract
We have obtained medium-resolution infrared K-band spectra of 44 giants in seven heavily reddened clusters in the Galactic bulge, as well as 12 giants in omega Centauri. We measure the equivalent widths of the Na doublet, the Ca triplet, and the CO band head, and then apply the new technique of Frogel et al. to determine the metallicity of each star. Averaging these values, we estimate the metallicity for each cluster and compare our new [Fe/H] values with previous determinations from the literature. Our estimates for each cluster are NGC 6256 ( - 1.35), NGC 6539 (-0.79), HP 1 (-1.30), Liller 1 (-0.36), Palomar 6 (-0.52), Terzan 2 (-0.87), and Terzan 4 (-1.62). We briefly discuss differences between the various [Fe/H] scales on which it was possible to base our calibration, which is found to be the largest uncertainty in using this technique to determine metallicities.