NOAO >   Observing Info >   Approved Programs >   2003B-0088

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Proposal Information for 2003B-0088


PI: James Schombert, Univ. of Oregon, js@abyss.uoregon.edu
Address: Dept. of Physics, 461 Willamette Hall, Eugene, OR 97403, USA

CoI: Karl Rakos, Inst. for Astronomy, Univ. of Vienna
CoI: H. Maitzen, Inst. for Astronomy, Univ. of Vienna

Title: Age/Metallicity Calibration for Old Stellar Populations

Abstract: This project is to develop a new technique to determine the mean age and metallicity in objects with old stellar populations (i.e., globular clusters and ellipticals) through the use of a narrow band filter system. Our current limitation is sufficient age range in our calibrating globular clusters and a detailed comparison of our results with galaxies that have high S/N spectroscopy. To resolve this, we propose to use the CTIO 1.3m to image a set of 42 LMC/SMC clusters with a greater range of age/metallicities than our northern cluster sample and to obtain surface photometry of a set of Fornax elliptical and S0 galaxies which have been modeled for age and metallicity by spectrophotometric means. This will allow us to compare, over the same regions examined by slit spectroscopy, the differences between age/metallicity as determined by line strengths and age/metallicity determined by the integrated shape of the underlying CMD. Why is this an immediate concern? The information from line indices indicates that lower luminosity galaxies are younger than more massive galaxies, in support of predictions by hierarchical clustering models of galaxy formation. However, the continuum colors studies indicate that low mass galaxies are older than massive systems. Our program presents a unique opportunity to compare the results from line studies with color information calibrated with integrated star cluster populations.


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