NOAO >   Observing Info >   Approved Programs >   2009B-0157

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Proposal Information for 2009B-0157


PI: Abhijit Saha, NOAO, saha@noao.edu
Address: 950 North Cherry Ave., Tucson, AZ 85719, USA

CoI: Knut Olsen, NOAO
CoI: Eline Tolstoy, Kapteyn Astronomical Institute
CoI: Thomas de Boer, Kapteyn Astronomical Institute
CoI: Giuseppina Battaglia, ESO
CoI: Andrew Cole, Univ. of Tasmania
CoI: Matthew Shetrone, Univ. Texas

Title: Deep Imaging of Nearby Dwarf Spheroidal Galaxies

Abstract: We propose to obtain the most detailed and accurate star formation and chemical evolution histories of two nearby southern dwarf spheroidal galaxies, Fornax and Sculptor, by means of Color Magnitude Diagram (CMD) analyses. This requires deep multi-color imaging with CTIO/MOSAIC calibrated to the highest standards to obtain accurate photometry of individual stars down to the oldest Main Sequence Turnoff (MSTO) stars over the entire galaxies. These CMDs will be combined with our spectroscopic surveys of the abundances and velocities of large numbers of individual Red Giant Branch stars in these galaxies. This will allow us to determine accurate time scales for chemical enrichment and thus, for the production mechanisms of different elements in supernovae explosions and stellar winds. This will enable us to quantify how different processes affected the evolution of these systems with time and the relation to their known stellar population gradients. We will observe the gradients at the MSTO level, and thus \it directly in terms of age. This will result in the most complete picture of the formation and evolution of any galactic system ever made.


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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