Talk abstract

We investigate the radial contraction of forming protoclusters using an extension of n-body techniques that incorporates the accretional growth of stars from a background potential. We target our experiments toward populous (n ~ 30000) clusters likely to experience collisions as a result of accretion-driven contraction, and we verify that in less extreme star forming environments like Orion, the stellar density is low enough that collisions are unimportant. We find that the character of the collision process is not such that it is a route toward smoothly filling the top end of the mass spectrum. Instead, runaway growth of one or two extreme objects occurs within less than 1 Myr after accretion stops, resulting in a few extreme objects with masses several times the maximum reached by accretion. We compare the characteristics of these clusters to massive galactic clusters like the Arches.