The early dynamical evolution of cool, clumpy star clusters

Richard J. Allison, Simon P. Goodwin*, Richard J. Parker, Simon F. Portegies Zwart, Richard de Grijs

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

134 Citations (Scopus)


Observations and theory both suggest that star clusters form subvirial (cool) with highly substructured distributions. We perform a large ensemble of N-body simulations of moderate-sized (N = 1000) cool, fractal clusters to investigate their early dynamical evolution. We find that cool, clumpy clusters dynamically mass segregate on a short time-scale, that Trapezium-like massive higher order multiples are commonly formed, and that massive stars are often ejected from clusters with velocities >10 km s-1 (cf. the average escape velocity of 2.5 km s-1). The properties of clusters also change rapidly on very short time-scales. Young clusters may also undergo core collapse events, in which a dense core containing massive stars is hardened due to energy losses to a halo of lower mass stars. Such events can blow young clusters apart with no need for gas expulsion. The warmer and less substructured a cluster is initially, the less extreme its evolution.

Original languageEnglish
Pages (from-to)1098-1107
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - Sept 2010
Externally publishedYes


  • stars: formation
  • stars: kinematics and dynamics


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