Evolution of the core radius, see Eq. (1), normalised to the initial core radius. The plots show the clusters with the Salpeter IMF or equal-mass stars, both isolated and embedded into the environment (as labelled in the legends, we note that the two black lines are almost superimposed). The left-hand plot shows the more compact models with r_vir = 0.7 pc, the right-hand one is for r_vir = 1.3 pc. The moments of core collapse are highlighted with a vertical line.