Abstract details

Most of our understanding about distant unresolved stellar systems comes from comparing integrated-light properties to population synthesis models. It is therefore crucial to calibrate the latter as well as possible by using integrated-light colors of star clusters that have reliable ages and metallicities derived from deep CMDs and/or high-resolution spectroscopy of individual giant stars. This is especially true for the near-infrared and mid-infrared domains, which contain important population diagnostics and are often used to derive masses of stellar systems in the local Universe and at high redshifts. However, most population synthesis models are still relatively poorly calibrated in these portions of the electromagnetic spectrum. In order to test and improve the performance of the SSP models we present a new database of 2MASS magnitudes and colors for a large sample of Magellanic Cloud star clusters. Along with new optical (VRI) and Spitzer/IRAC photometry which we collected for a significant number of star clusters in our sample, we put popular population synthesis models to the test and find (sometimes very) significant differences between model predictions and observed colors.