Institution(s): 1. The University of Cincinnati
The age and mass of unresolved or partially resolved stellar clusters can only be estimated using their integrated-light properties of magnitude and colors. Traditional Simple Stellar Population (SSP) models interpret these integrated properties assuming an infinite mass limit. This can lead to catastrophic failures in both age and mass determination when applied to real stellar clusters, particularly with total mass below 104 Msun. New, more sophisticated mass-dependent SSP models provide more accurate age and mass estimates, in better agreement with cluster age determinations using deep photometry Color-Magnitude Diagrams (CMD). But even these modern, mass-dependent SSP models can fail to estimate age and mass if the cluster contains a second stellar population. Our newest mass-dependent Multiple Stellar Populations (MSP) models show the influence of a second population of stars on the integrated light of these complex stellar clusters and their age estimates shows stronger agreement with CMD-derived stellar cluster ages.