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Maren Hempel |
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"Globular Clusters as
Stellar Population Probes" |
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Using integrated photometry or spectroscopy of globular cluster systems in combination with Single Stellar Population models is a widely used method to probe the age and metallicity in their host galaxies. With increasing distance spectroscopic surveys become more and more un-feasible and broad band photometry is the only possibility to conduct larger surveys. Here I will describe our method of deriving cumulative age distributions in extragalactic globular cluster systems, focusing on early-type galaxies. This method is based on combined optical and near-infrared photometry, which on one hand helps to lift the in-famous age-metallicity degeneracy of optical broad band colors, but also adds to the systematic uncertainty of the age and metallicity estimates. The reason for the latter are significant differences in the color predictions of the applied Single Stellar Population models, which are most noticeable in the infrared. To evaluate this uncertainty we started a project to obtain integrated near-IR photometry for Milky Way globular clusters for which independent age and metallicity estimates are available. I will also report briefly on how we will utilize the up-coming Vista Variable survey in the research described above. |