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Escape from a Crisis in Fokker-Planck Models

Published online by Cambridge University Press:  12 April 2016

Simon F. Portegies Zwart
Affiliation:
Department of Earth Sciences and Astronomy, College of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
Koji Takahashi
Affiliation:
Department of Earth Sciences and Astronomy, College of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan

Abstract

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Recent N-body simulations have shown that there is a serious discrepancy between the results of N-body simulations and the results of Fokker-Planck simulations for the evolution of globular and rich open clusters under the influence of the galactic tidal field. In some cases, the lifetime obtained from Fokker-Planck calculations is more than an order of magnitude smaller than those from N-body simulations. In this paper we show that the principal cause for this discrepancy is an oversimplified treatment of the tidal field used in previous Fokker-Planck simulations. We performed new Fokker-Planck calculations using a more appropriate implementation for the boundary condition of the tidal field. The implementation is only possible with anisotropic Fokker-Planck models, while all previous Fokker-Planck calculations rely on the assumption of isotropy. Our new Fokker-Planck results agree well with N-body results. Comparison of the two types of simulations gives a better understanding of the evolution of such clusters.

Type
Stellar Systems
Copyright
Copyright © Kluwer 1999

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