SCYON Abstract

Received on October 25 2007

Escape from the vicinity of fractal basin boundaries of a star cluster

Authors	Andreas Ernst, Andreas Just, Rainer Spurzem and Oliver Porth
Affiliation	Astronomisches Rechen-Institut am Zentrum für Astronomie der Universität Heidelberg
Accepted by	Monthly Notices of the Royal Astronomical Society
Contact	aernst@ari.uni-heidelberg.de
URL	http://www.arxiv.org/abs/0710.4485
Links

Abstract

The dissolution process of star clusters is rather intricate for theory. We investigate it in the context of chaotic dynamics. We use the simple Plummer model for the gravitational field of a star cluster and treat the tidal field of the Galaxy within the tidal approximation. That is, a linear approximation of tidal forces from the Galaxy based on epicyclic theory in a rotating reference frame. The Poincaré surfaces of section reveal the effect of a Coriolis asymmetry. The system is non-hyperbolic which has important consequences for the dynamics. We calculated the basins of escape with respect to the Lagrangian points L₁ and L₂. The longest escape times have been measured for initial conditions in the vicinity of the fractal basin boundaries. Furthermore, we computed the chaotic saddle for the system and its stable and unstable manifolds. The chaotic saddle is a fractal structure in phase space which has the form of a Cantor set and introduces chaos into the system.