2.5. Masses

SSCs are thought to have masses at least as large as 10⁴ M, and more likely between 10⁵ to 10⁶ M. Unfortunately, the estimated masses are highly uncertain because invariably they are derived from population synthesis models that depend on a large number of poorly constrained parameters. To obtain the total cluster mass, one must generally adopt a slope for the stellar initial mass function (IMF) and extrapolate it to low, essentially unobserved, masses. A more direct and reliable method to estimate the cluster masses will be described below.