Open AccessDynamical evolution of the Orion nebula cluster
Author(s) -
Scally Aylwyn,
Clarke Cathie,
McCaughrean Mark J.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08617.x
Subject(s) - physics , orion nebula , astrophysics , cluster (spacecraft) , virial theorem , star cluster , galaxy , stars , nebula , proper motion , star formation , galaxy cluster , astronomy , statistical physics , computer science , programming language
Observations of star formation in the Galaxy support the conclusion that most stars – including our own – form in an environment like the Orion nebula cluster (ONC). We construct a range of dynamical models of the ONC, using Aarseth's nbody6 code, and explore their consequences for the origins of the cluster and its subsequent evolution. We find that the most acceptable fits to the cluster density profile are obtained in models where the cluster is set up in virial equilibrium and where the cluster extends well outside the limits of existing photometric surveys. However, current estimates of the virial ratio suggest the cluster is already unbound. We show that the size and age of the ONC in this case imply either that it became unbound only very recently, or else that it has expanded quasi‐statically. In the latter case, its initial central density may have exceeded its current value by 1–2 orders of magnitude. We stress the importance of future proper motion experiments to distinguish between these possibilities.