Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2011-01-10
Mon. Not. R. Astron. Soc. 413, 2509-2524 (2011)
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
Updated to match final journal style
Scientific paper
10.1111/j.1365-2966.2011.18320.x
The evolution of globular clusters due to 2-body relaxation results in an outward flow of energy and at some stage all clusters need a central energy source to sustain their evolution. Henon provided the insight that we do not need to know the details of the energy production in order to understand the relaxation-driven evolution of the cluster, at least outside the core. He provided two self-similar solutions for the evolution of clusters based on the view that the cluster as a whole determines the amount of energy that is produced in the core: steady expansion for isolated clusters, and homologous contraction for clusters evaporating in a tidal field. We combine these models: the half-mass radius increases during the first half of the evolution, and decreases in the second half; while the escape rate approaches a constant value set by the tidal field. We refer to these phases as `expansion dominated' and `evaporation dominated'. These simple analytical solutions immediately allow us to construct evolutionary tracks and isochrones in terms of cluster half-mass density, cluster mass and galacto-centric radius. From a comparison to the Milky Way globular clusters we find that roughly 1/3 of them are in the second, evaporation-dominated phase and for these clusters the density inside the half-mass radius varies with the galactocentric distance R as rho_h ~ 1/R^2. The remaining 2/3 are still in the first, expansion-dominated phase and their isochrones follow the environment-independent scaling rho_h ~ M^2; that is, a constant relaxation time-scale. We find substantial agreement between Milky Way globular cluster parameters and the isochrones, which suggests that there is, as Henon suggested, a balance between the flow of energy and the central energy production for almost all globular clusters.
Gieles Mark
Heggie Douglas C.
Zhao HongSheng
No associations
LandOfFree
The life cycle of star cluster in a tidal field does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The life cycle of star cluster in a tidal field, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The life cycle of star cluster in a tidal field will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-456521