On Encounter Rates in Star Clusters

Close encounters between stars in star forming regions are important as they can perturb or destroy protoplanetary discs, young planetary systems, and stellar multiple systems. We simulate simple, viralised, equal-mass $N$-body clusters find that both the rate total number of varies by factors several statistically identical due to stochastic/chaotic details orbits dynamics. Encounters tend rapidly `saturate' core a cluster, with there each having many encounters, while more distant have none. However, we fraction had at least one encounter within particular distance grows same way (scaling crossing time half-mass radius) all clusters, present new (empirical) estimating distance.