Simulating Star Clusters with the AMUSE Software Framework: I.
  Dependence of Cluster Lifetimes on Model Assumptions and Cluster Dissolution
  Modes
  We perform a series of simulations of evolving star clusters using AMUSE (the
Astrophysical Multipurpose Software Environment), a new community-based
multi-physics simulation package, and compare our results to existing work.
These simulations model a star cluster beginning with a King model distribution
and a selection of power-law initial mass functions, and contain a tidal
cut-off. They are evolved using collisional stellar dynamics and include mass
loss due to stellar evolution. After determining that the differences between
AMUSE results and prior publications are understood, we explored the variation
in cluster lifetimes due to the random realization noise introduced by
transforming a King model to specific initial conditions. This random
realization noise can affect the lifetime of a simulated star cluster by up to
30%. Two modes of star cluster dissolution were identified: a mass evolution
curve that contains a run-away cluster dissolution with a sudden loss of mass,
and a dissolution mode that does not contain this feature. We refer to these
dissolution modes as "dynamical" and "relaxation" dominated respectively. For
Salpeter-like initial mass functions, we determined the boundary between these
two modes in terms of the dynamical and relaxation time scales.
