Tidal Disruption of Protoclusters in Giant Molecular Clouds

TL;DR

This study investigates how the proximity of massive objects within giant molecular clouds affects the collapse of protoclusters, providing criteria for when collapse can be considered isolated or disrupted.

Contribution

It offers numerical simulations that define the conditions under which protocluster collapse is significantly disrupted by nearby massive objects, considering disk geometries and observed velocities.

Findings

Collapse is disrupted within 2-4 pc of a 10^4 Msun mass.

Protoclusters more than ~4 pc away can collapse as if isolated.

Gravitational interactions do not disperse protocluster disks significantly.

Abstract

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 10^3 Msun protocluster initially a distance of 2-10 pc from a 10^3 - 10^6 Msun 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 protocluster collapse proceeds as if in isolation. For instance, we find the collapse of a 10^3 Msun protocluster will be significantly disrupted if it is within 2-4 pc of a 10^4 Msun point mass. Thus, the collapse of a 10^3 Msun protocluster can be considered to proceed as if in isolation if it is more than ~ 4 pc away from a 10^4 Msun 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.