Age and Metallicity Estimation of Globular Clusters from Stromgren Photometry

Abstract

We present a new technique for the determination of age and metallicity in composite stellar populations using Stromgren filters. Using principal component (PC) analysis on multi-color models, we isolate the range of values necessary to uniquely determine age and metallicity effects. The technique presented herein can only be applied to old (tau > 3 Gyrs) stellar systems composed of simple stellar populations, such as globular clusters and elliptical galaxies. Calibration using new photometry of 40 globular clusters with spectroscopic [Fe/H] values and main sequence fitted ages links the PC values to the Strömgren colors for an accuracy of 0.2 dex in metallicity and 0.5 Gyrs in age.

arXiv comment24 pages AAS LaTeX, 9 figures, accepted for publication in PASP

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• On the kinematic separation of field and cluster stars across the Bulge globular NGC 6528
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• Mid-UV Narrow-Band Indices of Evolved Simple Stellar Populations
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• The Ks-band Tully-Fisher Relation - A Determination of the Hubble Parameter from 218 ScI Galaxies and 16 Galaxy Clusters
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