NOAO >   Observing Info >   Approved Programs >   2015A-0419

# Program Information for 2015A-0419

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: Jeffrey Cummings, Johns Hopkins U.
CoI: Aaron Steinhauer, State University of New York Geneseo

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

Abstract: Building on successful surveys in NGC 3680 and NGC 6253, several 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 intermediate-band 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. We have: established the [Fe/H] dependence of star mass at the center of the MS Li-dip; found several Li-producing first-ascent giants in NGC 6819 and 2158; verified the coincidence between the warm- side of the MS Li-dip and a MS gap in NGC 7789, suggesting a link between the two. Here, we will extend our studies to metal-deficient clusters. We hope to obtain complete observations of NGC 2204, a cluster with age = 1.5-2.0 Gyr and [Fe/H] $\leq -0.30$, followed by NGC 2423 and 2506, which are similarly old but even more metal-poor. We will continue to survey for Li-rich giants, particularly below the red clump level. Finally, we will constrain proposed mechanisms for the formation of the Li-dip by improving knowledge of its {\it depth} in the Hyades and in Praesepe, which can distinguish between proposed mechanisms.

Program Type: ITAC

Scheduled Nights:
Run 2 (2015A):  WIYN/HYDR -- 4n on Feb 01 2015, Feb 05 - Feb 07 2015

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 >   2015A-0419