NOAO >   Observing Info >   Approved Programs >   2009B-0313

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Proposal Information for 2009B-0313


PI: Jason T. Wright, Cornell University, jtwright@astro.cornell.edu
Address: Astronomy Department, 226 Cornell University, Ithaca, NY 14850, USA

Title: Determining Distance, Age, and Activity in a New Benchmark Cluster: Ruprecht 147

Abstract: This proposal seeks 0.7 night of time on Hectochelle to observe the F, G, and K dwarfs of Ruprecht 147, recently identified as the closest old stellar cluster. At only ~ 200 pc and at an age of ~ 1-2 Gyr, this will be an important benchmark in stellar astrophysics, providing the \it only sample of spectroscopically accessible old, late-type stars of determinable age. Hectochelle is the ideal instrument to study this cluster, with a FOV, fiber count, and telescope aperture well matched to the cluster's diameter (~ 1^\circ), richness (~ 100 identified members), and distance modulus (6.5-7 mag., putting the G and K dwarfs at B=11-15). Hectochelle will measure the \caii line strengths of members to establish, for the first time, the chromospheric activity levels of a statistically significant sample of single, G and K dwarfs of this modest age. Hectochelle will also vet background stars for suitability as astrometric reference stars for a forthcoming HST FGS proposal to robustly measure the cluster's distance.


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



NOAO >   Observing Info >   Approved Programs >   2009B-0313

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