M. Hempel Abstract

Globular Clusters as Age Probes

M. Hempel (Pontificia Universidad Catolica de Chile)

Globular Clusters are known to be excellent probes to study the evolutionary history of their host galaxy, representing single stellar populations ALMOST perfectly and being observable to large distances, e.g. in the COMA galaxy cluster. The latter makes globular clusters extremely useful in galaxy surveys, studying the effects of different galaxy parameters on the evolution of the host galaxy. However, with increasing galaxy distance those surveys will be dominated by photometric methods, which are hampered by the age metallicity degeneracy.  The latter can be lifted by combining optical and near-infrared colors. In order to assess the accuracy of the photometric age determination we conduct a study on the globular cluster system of Milky Way and Magellanic Clouds, for which the ages and metallicities are known from independent studies. Our study is based on data obtained within the VISTA Variable Survey in the Via Lactea and additional data obtained with CTIO/NEWFIRM. Here we will present first results and discuss various specific problems and possible solutions.