The effects of young embedded groups and clusters on forming solar systems

Abstract

"Most stars--and hence most solar systems--form within groups or clusters. This contribution discusses how these star forming environments affect the planetary systems forming within them. The discussion starts with the dynamical evolution of young stellar clusters with N=100-1000 members. We use N-body simulations to explore how evolution depends on system size N and the initial conditions. Motivated by recent observations, this study compares subvirial and virial starting states. Multiple realizations of equivalent cases (100 simulations per case) are used to build up a robust statistical description of these systems, e.g. distributions of closest approaches and distributions of radial locations. These results provide a framework from which to assess the effects of clusters on planet formation. The distributions of radial positions are used in conjunction with far ultraviolet (FUV) luminosity distributions to determine the radiation exposure of circumstellar disks. Photoevaporation calculations then determine the efficacy of radiation in removing gas from the systems (resulting in loss of planet forming potential). The distributions of closest approaches are used in conjunction with scattering cross-sections (calculated from 100 000 numerical experiments) to determine the probability of solar system disruption. Our main result is that clusters in this size range can have a significant effect on forming planetary systems, and we have quantified the size of these effects. For example, in modest-sized clusters, FUV radiation typically leads to disk photoevaporation down to outer disk radii of 30-50 AU."