NOAO >   Observing Info >   Approved Programs >   2009A-0230

# Proposal Information for 2009A-0230

PI: Christian Johnson, Indiana University, cijohnson@astro.indiana.edu
Address: Astronomy Department, 727 East 3rd Street, Bloomington, IN 47405, USA

CoI: Catherine Pilachowski, Indiana University
CoI: Michael Rich, University of California Los Angeles
CoI: Jon Fulbright, Johns Hopkins University

Title: Chemical Evolution in Omega Centauri

Abstract: \beginraggedright The Galactic globular cluster Omega Centauri (\omega Cen) exhibits a huge metallicity spread spanning - 2.2\la[Fe/H]\la-0.6 that is contained in multiple, distinct stellar populations. \omega Cen's large chemical heterogeneity extends to all elements, suggesting the cluster experienced self-enrichment on a scale not seen in normal" globular clusters. By comparing the evolution of light and heavy elements, which have different production sources and timescales, it is possible to reconstruct the cluster's chemical history. Large, homogeneous samples are required to avoid selection and evolutionary biases and to accurately follow the chemical evolution with metallicity. Therefore, we propose to obtain Hydra spectra containing O, Na, (alpha), and Fe-peak abundances in a 100% complete sample down to V=13.5 by adding the remaining 360 red giant branch stars to our current sample containing ~70% of the bright giants. We also propose to obtain ~300 additional Hydra spectra that include Al, La (s-process), and Eu (r-process) lines to supplement our sample of 80 spectra in this region. These data will compliment a similar dataset of Galactic bulge giants. \endraggedright

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 NOAO >   Observing Info >   Approved Programs >   2009A-0230