NOAO >   Observing Info >   Approved Programs >   2010A-0395

Small NOAO Logo

Proposal Information for 2010A-0395


PI: Anna Frebel, Harvard-Smithsonian Center for Astrophysics, afrebel@cfa.harvard.edu
Address: 60 Garden St. MS-20, Cambridge, MA 02138, USA

CoI: Andrea Dupree, Harvard-Smithsonian Center for Astrophysics
CoI: Georges Meynet, Geneva Observatory

Title: Testing for the existence of massive Population III stars with stellar archaeology

Abstract: We propose to observationally test a new prediction that the most iron-poor Galactic halo star HE 1327-2326 with \mbox[Fe/H]=-5.4 had a massive rotating Population III progenitor. This would prove that this object is a true second-generation star, and that stellar rotation must have played an important role in the early universe. If this scenario is correct, the gas from which \mboxHE 1327-2326 formed should have been dramatically enriched in hydrogen-burning products (i.e. helium, with He fractions of up to 0.6) provided by the stellar wind of the fast-evolving PopIII star that underwent rotation-induced mixing. The He I line at 10830A will be observed with PHOENIX to confirm or refute this theory. Non-LTE semi-empirical modeling also making use of supplementary optical spectra will yield a He abundance. Should no He enhancement be found, the origin of the signature found in HE 1327-2326 must have come from a non-rotating, peculiar source whose chemical enrichment was mixed with large amounts of pristine material. Also, the controversial, unexplained Li-depletion in HE 1327-2326 must then be due to internal processes, a scenario which is not favored by its evolutionary status.


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 >   2010A-0395

noaoprop-help@noao.edu

Small NOAO Logo