2008ApJ...683..226P

We study the collapse of protoclusters within a giant molecular cloud (GMC) to determine the conditions under which collapse is significantly disrupted. Motivated by observations of star-forming regions which exhibit flattened cloud structures, this study considers collapsing protoclusters with disk geometries. The collapse of a 10³ M_☉ protocluster initially a distance of 2-10 pc from a 10³-10⁶ M_☉ point mass is numerically calculated. Simulations with zero initial relative velocity between the two are completed, as well as simulations with relative velocities consistent with those observed in GMCs. The results allow us to define the conditions under which it is safe to assume that protocluster collapse proceeds as if in isolation. For instance, we find that the collapse of a 10³ M_☉ protocluster will be significantly disrupted if it is within 2-4 pc of a 10⁴ M_☉ point mass. Thus, the collapse of a 10³ M_☉ protocluster can be considered to proceed as if in isolation if it is more than ∼4 pc away from a 10⁴ M_☉ compact object. In addition, in no portion of the sampled parameter space does the gravitational interaction between the protocluster disk and the massive particle significantly disperse the disk into the background GMC. We discuss the distribution of clusters of young stellar objects within the Perseus and Mon R2 star-forming regions, which are consistent with the results of our simulations and the limitations of our results in gas dominated regions such as the Orion cloud.