NOAO >   Observing Info >   Approved Programs >   2010B-0320

Small NOAO Logo

Proposal Information for 2010B-0320


PI: Catherine R. Kennedy, Michigan State University, kenne257@msu.edu
Address: Physics Department, Biomedical and Physical Sciences Building, East Lansing, MI 48824, USA

CoI: Timothy C. Beers, Michigan State University
CoI: Jennifer A. Johnson, The Ohio State University
CoI: Falk Herwig, University of Victoria
CoI: Norbert Christlieb, University of Heidelberg

Title: Nitrogen Abundances for Carbon-Enhanced Metal-Poor Stars

Abstract: While nitrogen is a common element in the cosmos, the site(s) of its manufacture remain uncertain. Theoretical models suggest that the main source of primary nitrogen should be hot bottom burning in intermediate- mass AGB stars. While this has been validated by direct measurements of C and N in AGB stars in the LMC, very few Galactic CEMP stars observed to date exhibit strong enhancements of nitrogen. In order to provide the fundamental data required to firmly establish the astrophysical origin of nitrogen, or refute its exclusive origin in early generation AGB stars, we propose to measure the abundance of N for a sample of ~ 50 carbon-enhanced metal-poor stars. Our plan is to measure N from the NH band at 3360 \AA. This method of estimating nitrogen is superior to the only alternative at medium resolution, from the CN band, since the strength of CN features in optical spectra depend strongly on the abundance of carbon, rendering it far more uncertain. Our program stars already have C and O abundances from previously obtained medium-resolution spectra; with the addition of N, we will obtain the largest set of carbon-enhanced metal- poor stars to date with a full inventory of CNO abundance measurements.


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 >   2010B-0320

noaoprop-help@noao.edu

Small NOAO Logo