Dr. Fred Adams, University of Michigan

"The Effects of Groups/Clusters on Forming Solar Systems"

Abstract:
Most stars -- and hence most solar systems -- form within groups or
clusters. This talk discusses how these star forming environments can
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 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 conclusion is that clusters in this size range have
a modest effect on forming planetary systems, and we can quantify the
size of these effects.