WIYN OPEN CLUSTER STUDY. XXIV. STELLAR RADIAL-VELOCITY MEASUREMENTS IN NGC 6819
- Astronomy Department, University of Wisconsin-Madison, 475 N Charter St, Madison, WI 53706 (United States)
- Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
We present the current results from our ongoing radial-velocity (RV) survey of the intermediate-age (2.4 Gyr) open cluster NGC 6819. Using both newly observed and other available photometry and astrometry, we define a primary target sample of 1454 stars that includes main-sequence, subgiant, giant, and blue straggler stars, spanning a magnitude range of 11 {<=}V{<=} 16.5 and an approximate mass range of 1.1-1.6 M {sub sun}. Our sample covers a 23 arcminute (13 pc) square field of view centered on the cluster. We have measured 6571 radial velocities for an unbiased sample of 1207 stars in the direction of the open cluster NGC 6819, with a single-measurement precision of 0.4 km s{sup -1} for most narrow-lined stars. We use our RV data to calculate membership probabilities for stars with {>=}3 measurements, providing the first comprehensive membership study of the cluster core that includes stars from the giant branch through the upper main sequence. We identify 480 cluster members. Additionally, we identify velocity-variable systems, all of which are likely hard binaries that dynamically power the cluster. Using our single cluster members, we find a cluster average RV of 2.34 {+-} 0.05 km s{sup -1}. We use our kinematic cluster members to construct a cleaned color-magnitude diagram from which we identify rich giant, subgiant, and blue straggler populations and a well defined red clump. The cluster displays a morphology near the cluster turnoff clearly indicative of core convective overshoot. Finally, we discuss a few stars of note, one of which is a short-period red-clump binary that we suggest may be the product of a dynamical encounter.
- OSTI ID:
- 21255693
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 1 Vol. 138; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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