Runaway massive stars from R136: VFTS 682 is very likely a "slow
  runaway"
  We conduct a theoretical study on the ejection of runaway massive stars from
R136 --- the central massive, star-burst cluster in the 30 Doradus complex of
the Large Magellanic Cloud. Specifically, we investigate the possibility of the
very massive star (VMS) VFTS 682 being a runaway member of R136. Recent
observations of the above VMS, by virtue of its isolated location and its
moderate peculiar motion, have raised the fundamental question whether isolated
massive star formation is indeed possible. We perform the first realistic
N-body computations of fully mass-segregated R136-type star clusters in which
all the massive stars are in primordial binary systems. These calculations
confirm that the dynamical ejection of a VMS from a R136-like cluster, with
kinematic properties similar to those of VFTS 682, is common. Hence the
conjecture of isolated massive star formation is unnecessary to account for
this VMS. Our results are also quite consistent with the ejection of 30 Dor
016, another suspected runaway VMS from R136. We further note that during the
clusters' evolution, mergers of massive binaries produce a few single stars per
cluster with masses significantly exceeding the canonical upper-limit of 150
solar mass. The observations of such single super-canonical stars in R136,
therefore, do not imply an IMF with an upper limit greatly exceeding the
accepted canonical 150 solar mass limit, as has been suggested recently, and
they are consistent with the canonical upper limit.
