NOAO >   Observing Info >   Approved Programs >   2003B-0173

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Proposal Information for 2003B-0173


PI: Verne V. Smith, University of Texas at El Paso, verne@barium.physics.utep.edu
Address: Dept. of Physics, 500 W. University, El Paso, Texas 79968, USA

CoI: Katia Cunha, Observatorio Nacional, Rio de Janeiro, Brazil
CoI: Kenneth H. Hinkle, Kitt Peak National Observatory

Title: Chemical Evolution in the Large Magellanic Cloud from Infrared Spectroscopy of Red Giants

Abstract: High-resolution infrared spectroscopy will be conducted on a sample of Large Magellanic Cloud red giants using Gemini South with Phoenix. Abundances of carbon, nitrogen, oxygen, fluorine, sodium, scandium, titanium, iron, and nickel can be derived accurately from red giants using a combination of atomic lines and molecular lines from CO, OH, CN, and HF. In our earlier analysis of 12 LMC field red giants, using high- resolution IR spectra from Phoenix, we demonstrated conclusively that in the more metal-rich stars of the LMC, the abundance ratio of oxygen to iron (expressed as [O/Fe]) falls below Galactic values at the same iron abundances ([Fe/H]~ -0.3 to -0.5). As the [O/Fe] ratio depends upon star formation histories in a stellar population, comparative studies of [O/Fe] versus [Fe/H] can provide constraints on star formation histories and chemical evolution within galaxies. In this proposal, we will add 9 more LMC field red giants that will more evenly sample the field LMC [Fe/H] distribution, down to [Fe/H]~=-1.5. These results will provide strong constraints on chemical evolution models for the LMC.


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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