NOAO >   Observing Info >   Approved Programs >   2011B-0514

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Proposal Information for 2011B-0514


PI: Christian Johnson, University of California, Los Angeles, cijohnson@astro.ucla.edu
Address: Physics Department, 430 Portoloa Plaza, Box 951547, Los Angeles, CA 90095--1547, USA

CoI: Michael Rich, University of California, Los Angeles
CoI: Roberto de Propris, Cerro Tololo Inter--American Observatory
CoI: Andrea Kunder, Cerro Tololo Inter--American Observatory

Title: Chemical Abundances and the Formation and Evolution of the Galactic Bulge

Abstract: Understanding the detailed structure and composition of the Galactic bulge is crucial for decoding the formation history of the Milky Way and interpreting observations of extragalactic and/or unresolved stellar populations. Previous high resolution spectroscopic analyses of individual bulge stars have focused almost exclusively on [Fe/H] abundance measurements, and have been mostly limited to ~3-4 fields located along the bulge minor axis. However, obtaining detailed kinematic and chemical composition data for large samples of stars in multiple bulge regions is critical to understanding how the bulge formed and how it may have interacted with the Galactic disk and halo populations. Investigating the chemical abundance patterns of light odd- Z, (alpha), Fe-peak, and neutron-capture elements, which are indicators of different production sources and timescales, allows us to reconstruct a stellar population's evolutionary history. Therefore, we are proposing to complete a project aimed at determining the chemical composition of ~1,000 Galactic bulge giants in 11 minor-axis and off-axis fields spanning a large portion of the bulge. These data will be obtained with the Blanco 4m telescope and Hydra Echelle spectrograph, and will be combined with a similar sample of already published \omega Centauri stars to provide insight into the chemical evolution of two independently evolving populations that span a metallicity range of ~1,000. We are also proposing to further investigate the nature of a sub-population of foreground metal-rich, (alpha)-rich red clump stars serendipitously discovered in our currently existing data set.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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