A highly efficient measure of mass segregation in star clusters
  Investigations of mass segregation are of vital interest for the
understanding of the formation and dynamical evolution of stellar systems on a
wide range of spatial scales. Our method is based on the minimum spanning tree
(MST) that serves as a geometry-independent measure of concentration. Compared
to previous such approaches we obtain a significant refinement by using the
geometrical mean as an intermediate-pass. It allows the detection of mass
segregation with much higher confidence and for much lower degrees of mass
segregation than other approaches. The method shows in particular very clear
signatures even when applied to small subsets of the entire population. We
confirm with high significance strong mass segregation of the five most massive
stars in the Orion Nebula Cluster (ONC). Our method is the most sensitive
general measure of mass segregation so far and provides robust results for both
data from simulations and observations. As such it is ideally suited for
tracking mass segregation in young star clusters and to investigate the long
standing paradigm of primordial mass segregation by comparison of simulations
and observations.
