S316.8.04 — Cluster assembly in hierarchically collapsing molecular clouds

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Aug 13th at 9:30 AM until 9:50 AM

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Author(s): Enrique Vazquez-Semadeni1

Institution(s): 1. UNAM

I will discuss the mechanism of cluster formation in hierarchically collapsing molecular clouds. Recent evidence, both observational and numerical, suggests that molecular clouds (MCs) may be undergoing global, hierarchical gravitational collapse. The "hierarchical" regime consists of small-scale collapses within larger-scale ones. The former occur in a more scattered fashion and at slightly earlier times, and are themselves falling into the larger potential well of the still-ongoing large-scale collapse. Instead, the large-scale collapse culminates a few Myr later, in a highly focused region, of higher density, mass, and velocity dispersion. The stars formed in the early, small-scale collapses share the infall velocity of their parent clumps towards the larger potential trough, while those formed later, in the aforementioned trough, form from gas that has already dissipated some of its kinetic energy, and thus have a lower velocity dispersion. This leads to a radial age gradient in the stellar population, in agreement with recent observations.