THE FORMATION AND DYNAMICAL EVOLUTION OF YOUNG STAR CLUSTERS

ABSTRACT Recent observations have revealed a variety of young star clusters, including embedded systems, young massive clusters, and associations. We study the formation and dynamical evolution of these clusters using a combination of simulations and theoretical models. Our simulations start with a...

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Bibliographic Details
Published in:The Astrophysical journal 2016-01, Vol.817 (1), p.4
Main Authors: Fujii, M. S., Zwart, S. Portegies
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Computer simulation
COSMIC GASES
Evolutionary
galaxies: star clusters: general
GRAVITATION
ISM: clouds
MASS
Massive stars
methods: numerical
MILKY WAY
Milky Way Galaxy
Molecular clouds
Open clusters
open clusters and associations: general
RELAXATION
SIMULATION
STAR CLUSTERS
STAR EVOLUTION
STARS
Stellar evolution
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Summary:ABSTRACT Recent observations have revealed a variety of young star clusters, including embedded systems, young massive clusters, and associations. We study the formation and dynamical evolution of these clusters using a combination of simulations and theoretical models. Our simulations start with a turbulent molecular cloud that collapses under its own gravity. The stars are assumed to form in the densest regions in the collapsing cloud after an initial free-fall time of the molecular cloud. The dynamical evolution of these stellar distributions is continued by means of direct N-body simulations. The molecular clouds typical of the Milky Way Galaxy tend to form embedded clusters that evolve to resemble open clusters. The associations were initially considerably more clumpy, but they lost their irregularity in about a dynamical timescale, due to the relaxation process. The densest molecular clouds, which are absent in the Milky Way but are typical in starburst galaxies, form massive, young star clusters. They indeed are rare in the Milky Way. Our models indicate a distinct evolutionary path from molecular clouds to open clusters and associations or to massive star clusters. The mass-radius relation for both types of evolutionary tracks excellently matches the observations. According to our calculations, the time evolution of the half-mass-radius relation for open clusters and associations follows , whereas for massive star clusters . Both trends are consistent with the observed age-mass-radius relation for clusters in the Milky Way.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/817/1/4