SIMBAD references

Using the NIRSPEC spectrograph at Keck II, we have obtained echelle spectra covering the range 1.5-1.8 µm for two 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±0.1 (from the OH lines) for the giants in both clusters. We measure strong lines for the α-elements Mg, Ca, and Si, but the lower sensitivity of these lines to abundance permits us only to state a general [α/Fe]=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 scenario in which the clusters formed early, with rapid enrichment. We have difficulty achieving 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 α-element enhancements are adopted, respectively.