The Gaia-ESO Survey: N-body modelling of the Gamma Velorum cluster
  The Gaia-ESO Survey has recently unveiled the complex kinematic signature of
the Gamma Velorum cluster: this cluster is composed of two kinematically
distinct populations (hereafter, population A and B), showing two different
velocity dispersions and a relative ~2 km s^-1 radial velocity (RV) shift. In
this paper, we propose that the two populations of the Gamma Velorum cluster
originate from two different sub-clusters, born from the same parent molecular
cloud. We investigate this possibility by means of direct-summation N-body
simulations. Our scenario is able to reproduce not only the RV shift and the
different velocity dispersions, but also the different centroid (~0.5 pc), the
different spatial concentration and the different line-of-sight distance (~5
pc) of the two populations. The observed 1-2 Myr age difference between the two
populations is also naturally explained by our scenario, in which the two
sub-clusters formed in two slightly different star formation episodes. Our
simulations suggest that population B is strongly supervirial, while population
A is close to virial equilibrium. We discuss the implications of our models for
the formation of young star clusters and OB associations in the Milky Way.
