ar X iv : a st ro - p h / 06 01 02 7 v 1 2 J an 2 00 6 The metallicity of the old open cluster NGC 6791 1

ar X iv : a st ro - p h / 06 04 03 0 v 1 3 A pr 2 00 6 High resolution infrared spectroscopy of the old open cluster NGC 6791

We report abundance analysis for 6 M giant members of the old open cluster NGC 6791, based on infrared spectroscopy (1.5−1.8 μm) at R=25,000, using the NIRSPEC spectrograph at the Keck II telescope. We find the iron abundance 〈[Fe/H]〉 = +0.35 ± 0.02, confirming the super solar metallicity of this cluster derived from optical medium-high resolution spectroscopy. We also measure C, O and other al...

ar X iv : a st ro - p h / 02 10 42 0 v 1 1 8 O ct 2 00 2 Extragalactic Globular Clusters in the Near - Infrared

Visual and near-infrared colours are used to identify intermediate-age globular cluster in early-type galaxies. In NGC 5846 and NGC 4365 colour-colour diagrams (V-I vs. V-K) reveal a sub-population in the globular cluster systems with an age much younger than the expected old populations (13-15 Gyr). A comparison with SSP models dates the formation of this younger population 2-7 Gyr back. Furth...

ar X iv : a st ro - p h / 06 12 42 6 v 1 1 5 D ec 2 00 6 Heating and Cooling in the Perseus Cluster Core

ar X iv : a st ro - p h / 01 11 13 6 v 1 7 N ov 2 00 1 1 Active Optics in Modern , Large Optical Telescopes

ar X iv : a st ro - p h / 02 03 45 4 v 2 1 7 M ay 2 00 2 New Members of the Cluster Family in Nearby Lenticulars

Using spectra obtained with the Keck I telescope we have demonstrated conclusively that the faint (23≤V≤ 24 mag.) and unusually extended objects we discovered in HST images of the lenticular galaxies, NGC 1023 and NGC 3384, are star clusters associated with their respective galaxies. In the case of NGC 1023 we were further able to establish that these objects are old (≥7–8 Gyr), moderately meta...