Spectroscopic Abundances in the Open Cluster, NGC 6819

Abstract

High-dispersion spectra of 333 stars in the open cluster NGC 6819, obtained using the HYDRA spectrograph on the WIYN 3.5m telescope, have been analyzed to determine the abundances of iron and other metals from lines in the 400 A region surrounding the Li 6708 A line. Our spectra, with signal-to-noise per pixel (SNR) ranging from 60 to 300, span the luminosity range from the tip of the red giant branch to a point two magnitudes below the top of the cluster turnoff. We derive radial and rotational velocities for all stars, as well as [Fe/H] based on 17 iron lines, [Ca/H], [Si/H], and [Ni/H] in the 247 most probable, single members of the cluster. Input temperature estimates for model atmosphere analysis are provided by (B-V) colors merged from several sources, with individual reddening corrections applied to each star relative to a cluster mean of E(B-V) = 0.16. Extensive use is made of ROBOSPECT, an automatic equivalent width measurement program; its effectiveness on large spectroscopic samples is discussed. From the sample of likely single members, [Fe/H] = -0.03 +/- 0.06, where the error describes the median absolute deviation about the sample median value, leading to an internal precision for the cluster below 0.01 dex. The final uncertainty in the cluster abundance is therefore dominated by external systematics due to the temperature scale, surface gravity, and microturbulent velocity, leading to [Fe/H] = -0.02 +/- 0.02 for a sub-sample restricted to main sequence and turnoff stars. This result is consistent with our recent intermediate-band photometric determination of a slightly subsolar abundance for this cluster. [Ca/Fe], [Si/Fe], and [Ni/Fe] are determined to be solar within the uncertainties. NGC 6819 has an abundance distribution typical of solar metallicity thin disk stars in the solar neighborhood.

arXiv commentWIYN Open Cluster Study LXV; accepted to Astronomical Journal. 16 pages, 5 figures, 3 tables

References in corpus (19)

• Cosmic-Ray Rejection by Laplacian Edge Detection
• The Tenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Apache Point Observatory Galactic Evolution Experiment
• The effective temperature scale of FGK stars. II. Teff : color : [Fe/H] calibrations
• Kepler Asteroseismology Program: Introduction and First Results
• Some Revised Observational Constraints on the Formation and Evolution of the Galactic Disk
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Oxygen Abundances in Nearby FGK Stars and the Galactic Chemical Evolution of the Local Disk and Halo
• Metal Abundances of Red Clump Stars in Open Clusters: I. NGC 6819
• Sounding open clusters: asteroseismic constraints from Kepler on the properties of NGC 6791 and NGC 6819
• A High Relative-Precision Color-Magnitude Diagram of M67
• The CFHT Open Star Cluster Survey II -- Deep CCD Photometry of the Old Open Star Cluster NGC 6819
• WIYN Open Cluster Study. XXIV. Stellar Radial-Velocity Measurements in NGC 6819
• WIYN Open Cluster Study. LX. Spectroscopic Binary Orbits in NGC 6819
• Lithium in the Intermediate-Age Open Cluster, NGC 3680
• A Lithium-Rich Red Giant Below the Clump in the Kepler Cluster, NGC 6819
• WIYN Open Cluster Study : Wide-Field CCD Photometry of the Old Open Cluster NGC 6819
• WIYN Open Cluster Study. XXXIX. Abundances in NGC 6253 from HYDRA Spectroscopy of the Li 6708 A Region
• ROBOSPECT: Automated Equivalent Width Measurement
• A UBVI and uvbyCaHbeta Analysis of the Intermediate-Age Open Cluster, NGC 5822

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