We have obtained spectra for 1273 stars using the 0.9 m coudé feed telescope at Kitt Peak National Observatory. This telescope feeds the coudé spectrograph of the 2.1 m telescope. The spectra have been obtained with the no. 5 camera of the coudé spectrograph and a Loral 3K ; 1K CCD. Two gratings have been used to provide spectral coverage from 3460 to 9464 8, at a resolution of $1 8 FWHM and at an original dispersion of 0.44 8 pixel À1 . For 885 stars we have complete spectra over the entire 3460 to 9464 8 wavelength region (neglecting small gaps of less than 50 8), and partial spectral coverage for the remaining stars. The 1273 stars have been selected to provide broad coverage of the atmospheric parameters T eff , log g, and [Fe/H], as well as spectral type. The goal of the project is to provide a comprehensive library of stellar spectra for use in the automated classification of stellar and galaxy spectra and in galaxy population synthesis. In this paper we discuss the characteristics of the spectral library, viz., details of the observations, data reduction procedures, and selection of stars. We also present a few illustrations of the quality and information available in the spectra. The first version of the complete spectral library is now publicly available from the National Optical Astronomy Observatory (NOAO) via ftp and http.

We present new high signal-to-noise spectroscopic data on the M31 globular cluster (GC) system, obtained with the Hectospec multifiber spectrograph on the 6.5 m MMT. More than 300 clusters have been observed at a resolution of 5 Å and with a median S/N of 75 per Å, providing velocities with a median uncertainty of 6 km s −1 . The primary focus of this paper is the determination of mean cluster metallicities, ages, and reddenings. Metallicities were estimated using a calibration of Lick indices with [Fe/H] provided by Galactic GCs. These match well the metallicities of 24 M31 clusters determined from Hubble Space Telescope color-magnitude diagrams, the differences having an rms of 0.2 dex. The metallicity distribution is not generally bimodal, in strong distinction with the bimodal Galactic globular distribution. Rather, the M31 distribution shows a broad peak, centered at [Fe/H] = −1, possibly with minor peaks at [Fe/H] = −1.4, −0.7, and −0.2, suggesting that the cluster systems of M31 and the Milky Way had different formation histories. Ages for clusters with [Fe/H] > −1 were determined using the automatic stellar population analysis program EZ_Ages. We find no evidence for massive clusters in M31 with intermediate ages, those between 2 and 6 Gyr. Moreover, we find that the mean ages of the old GCs are remarkably constant over about a decade in metallicity (−0.95 [Fe/H] 0.0).

We present an updated catalog of 1300 objects in the field of M31, including 670 likely star clusters of various types, the rest being stars or background galaxies once thought to be clusters. The coordinates in the catalog are accurate to 0.2˝, and are based on images from the Local Group Survey (LGS, Massey et al. 2006) or from the DSS. Archival HST images and the LGS were inspected to confirm cluster classifications where possible, but most of the classifications are based on spectra taken of ∼ 1000 objects with the Hectospec fiber positioner and spectrograph on the 6.5m MMT. The spectra and images of young clusters are analyzed in detail in this paper; analysis of older clusters will appear in a later paper. Ages and reddenings of 140 young clusters are derived by comparing the observed spectra with model spectra. Seven of these clusters also have ages derived from HST color-magnitude diagrams (two of which we present here); these agree well with the spectroscopically determined ages. Combining new V band photometry with the M/L values that correspond to the derived cluster ages, we derive masses for the young clusters, finding them to have masses as great as 10 5 with a median of 10 4 M ⊙ , and a median age of 0.25 Gyr. In comparison therefore, Milky Way open clusters have the lowest median mass, the Milky Way and M31 globulars the highest, and the LMC young massive clusters and the M31 young clusters are in between. The young clusters in M31 show a range of structure. Most have the low concentration typical of Milky Way open clusters, but there are a few which have high concentrations. We expect that most of these young clusters will be disrupted in the next Gyr or so, however, some of the more massive and concentrated of the young clusters will likely survive for longer. The spatial distribution of the young clusters is well correlated with the star-forming regions as mapped out by mid-IR emission. A kinematic analysis likewise confirms the spatial association of the young clusters with the star forming young disk in M31.

We present a new library of integrated spectra of 40 Galactic globular clusters, obtained with the Blanco 4-m telescope and the R-C spectrograph at the Cerro Tololo Interamerican Observatory. The spectra cover the range ~ 3350 -- 6430 A with ~ 3.1 A (FWHM) resolution. The spectroscopic observations and data reduction were designed to integrate the full projected area within the cluster core radii in order to properly sample the light from stars in all relevant evolutionary stages. The S/N values of the flux-calibrated spectra range from 50 to 240/A at 4000 A and from 125 to 500/A at 5000 A. The selected targets span a wide range of cluster parameters, including metallicity, horizontal-branch morphology, Galactic coordinates, Galactocentric distance, and concentration. The total sample is thus fairly representative of the entire Galactic globular cluster population and should be valuable for comparison with similar integrated spectra of unresolved stellar populations in remote systems. For most of the library clusters, our spectra can be coupled with deep color-magnitude diagrams and reliable metal abundances from the literature to enable the calibration of stellar population synthesis models. In this paper we present a detailed account of the observations and data reduction. The spectral library is publicly available in electronic format from the National Optical Astronomical Observatory website.Comment: 39 Pages, including 2 tables and 15 Figures. To appear in the Astrophysical Journal, Supplement Serie

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