PI: Paul Goudfrooij, STScI, firstname.lastname@example.org
Address: INS, 3700 San Martin Drive, Baltimore, MD 21218, USA
CoI: Peter Pessev, STScI
CoI: Rupali Chandar, STScI
CoI: Thomas H. Puzia, STScI
CoI: Thomas M. Brown, STScI
Title: How Accurately Can We Determine Ages and Metallicities of Stellar Systems Using Integrated-Light Spectroscopy?
Abstract: Globular clusters are simple stellar populations which provide fundamental age/metallicity templates for the interpretation of extragalactic stellar systems. We are collecting a large, multi- wavelength dataset for an appropriately large number of Galactic globular clusters and intermediate-age (> 0.5 Gyr) globular clusters in the Magellanic Clouds. All targets have high-quality age and metallicity determinations available from color-magnitude diagrams. As part of this comprehensive dataset (which will be made available to the community), we propose to obtain high-quality integrated-light spectra (covering the Lick indices and the Ca II triplet) of a sample of globular clusters in the Milky Way and in the Magellanic Clouds. Our immediate objectives are to: \it (i) provide, for the first time, \it empirical relations among Lick & Ca II line strengths, ages, and metalliticies %and (alpha)/Fe ratios for for simple stellar populations; \it (ii) establish the scatter inherent in the observed line strengths of GCs at given ages and metallicities; \it (iii) quantify and calibrate the influence of horizontal branch morphology variations for old GCs at different metallicities, \it (iv) test the systematic accuracy of age and metallicity determinations using the latest population synthesis models. \bf This is a resubmission of a previously accepted long-term proposal, to make up for time lost due to bad weather and to complete crucial intermediate age Magellanic Clouds globular clusters and intermediate metallicity globular clusters in our Galaxy.
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