NOAO >   Observing Info >   Approved Programs >   2015B-0816

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Program Information for 2015B-0816


PI: Constantine Deliyannis, Indiana U., con@astro.indiana.edu
Address: Department of Astronomy, Bloomington, IN 47405-7105 USA

CoI: Barbara Anthony-Twarog, U. of Kansas
CoI: Bruce A Twarog, U. of Kansas
CoI: Aaron Steinhauer, State University of New York Geneseo

Title: Constraining the Evolution and Origin of Li Via Open Clusters: NGC 2204/2243/2506, and NGC 188

Abstract: Building on successful surveys in NGC 3680 and NGC 6253, a few years ago we undertook to obtain Li abundances for statistically significant samples of (250 - 350) stars in each of the open clusters NGC 2158, 6811, 6819 and 7789. We have combined Stromgren photometry with high- dispersion spectroscopy to map the main-sequence (MS) and post-MS surface evolution of Li for clusters of varying age and metallicity. In addition to establishing the [Fe/H] dependence of star mass at the center of the MS Li-dip, we have found several Li-rich first-ascent giants in NGC 6819 and 2158 and have verified the coincidence between the warm-side of the MS Li-dip and a MS gap in NGC 7789, suggesting a link between convection-induced gaps and the development of the dip. Here, we extend to metal-deficient and/or very old clusters. This winter we completed observations of NGC 2204, a cluster in the 1.5-2.0 Gyr range with [Fe/H] below -0.30, and began observing NGC 2243 and NGC 2506, which are even more metal-poor, which we now wish to complete. We will also begin studying dwarfs in the iconic NGC 188 at 7 Gyr. We will continue to survey for Li-rich giants, particularly below the red clump level. We will also probe the connection (if any) between the cluster's original Li abundance, exemplified by the unmodified Li abundance of stars above the MS dip, and cluster [Fe/H], as a way to gain insight into galactic Li evolution and cosmology.

Program Type: ITAC

Scheduled Nights:
Run 1 (2015B):  WIYN/HYDR -- 8n on Sep 14 - Sep 15 2015, Jan 06 - Jan 11 2016


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 >   2015B-0816

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