Tidal mass loss in star clusters and treatment of escapers in Fokker-Planck models

Takahashi, K. and Baumgardt, H. (2012) Tidal mass loss in star clusters and treatment of escapers in Fokker-Planck models. Monthly Notices of the Royal Astronomical Society, 420 2: 1799-1808. doi:10.1111/j.1365-2966.2011.20183.x


Author Takahashi, K.
Baumgardt, H.
Title Tidal mass loss in star clusters and treatment of escapers in Fokker-Planck models
Journal name Monthly Notices of the Royal Astronomical Society   Check publisher's open access policy
ISSN 0035-8711
1365-2966
Publication date 2012-02
Sub-type Article (original research)
DOI 10.1111/j.1365-2966.2011.20183.x
Open Access Status DOI
Volume 420
Issue 2
Start page 1799
End page 1808
Total pages 10
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2013
Language eng
Formatted abstract
This paper presents a new scheme to treat escaping stars in the orbit-averaged Fokker–Planck models of globular star clusters in a galactic tidal field. The existence of a large number of potential escapers, which have energies above the escape energy but are still within the tidal radius, is taken into account in the models. The models allow potential escapers to experience gravitational scatterings before they leave clusters and thus some of them may lose enough energy to be bound again. It is shown that the mass evolution of the Fokker–Planck models is in good agreement with that of N-body models including the full tidal-force field. The mass-loss time does not simply scale with the relaxation time due to the existence of potential escapers; it increases with the number of stars more slowly than the relaxation time, though it  tends to be proportional to the relaxation time in the limit of a weak tidal field. The Fokker–Planck models include two parameters: the coefficient γ in the Coulomb logarithm ln (γN) and the coefficient νe controlling the efficiency of the mass loss. The values of these parameters are determined by comparing the Fokker–Planck models with the N-body models. It is found that the parameter set (γ , νe) = (0.11, 7) works well for both single-mass and multimass clusters, but that the parameter set (γ , νe) = (0.02, 40) is another possible choice for multimass clusters.
Keyword Methods: numerical
Globular clusters: general
Galaxies: star clusters: general
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2013 Collection
 
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