NOAO >   Observing Info >   Approved Programs >   2003A-0395

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Proposal Information for 2003A-0395


PI: Peter M. Frinchaboy, University of Virginia, pmf8b@virginia.edu
Address: Department of Astronomy, P.O. Box 3818, Charlottesville, VA 22903, USA

CoI: Steven R. Majewski, University of Virginia
CoI: William E. Kunkel, Las Campanas Observatory
CoI: Randy L. Phelps, California State University, Sacramento
CoI: Michael F. Skrutskie, University of Virginia
CoI: Helio J. Rocha-Pinto, University of Virginia

Title: The Absolute Space Motions of Galactic Clusters

Abstract: My thesis project proposes to derive the orbits of a large sample of Galactic open clusters through use of Hydra multifiber spectroscopy. There have been three large surveys to determine Galactic cluster proper motions based on presumed cluster stars contained in the Hipparcos, Tycho-2, and the Four Million Star (4M) proper motion catalogs, resulting in published motions for 290 total clusters. However, a comparison of the derived motions for 101 clusters in common between the Hipparcos/Tycho2 and 4M surveys reveals a distressing amount of discrepancy, with well more than the stated uncertainties in almost every case. A primary source of the differences is the problem of identifying true cluster members in the proper motion surveys, given that many open clusters are in very crowded fields. Therefore, we propose to use precision radial velocities (RVs) to verify cluster membership for the stars used to define the cluster proper motions. The very precise mean RV of each cluster, which, when combined with the corrected proper motions, will allow us to determine the orbits of these clusters, and also to improve the age-dating of the clusters. Dynamical data on a large number of these clusters will be helpful not only to understanding the evolution of open clusters, but also the dynamical and chemical evolution of the disk.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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