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H.U. Keller, S. Eggers, W.J. Markiewicz (Max-Planck-Institut fuer Aeronomie)
Assuming that the solar system formed in a star cluster, the dynamical fate of its comet population is investigated. Firstly, we present a study of stellar perturbations of cometary orbits in the extended Kuiper belt (out to 100 AU). Normally, this region is hardly perturbed by outside influences. However, because of the higher stellar number density and the lower relative velocities between the stars in the cluster, significant inclinations and eccentricities can be induced, especially in the outer region of the belt. Secondly, major parts of the comets are lost from the forming stellar systems into interstellar space. At the same time some of these comets are captured from intra-cluster space and populate the outer solar system. The significance of this contribution will be discussed and numerical results will be presented. A further consequence of the star cluster scenario (presented elsewhere) is that scattering of the planetesimals by the four giant planets and perturbations by cluster stars lead to the formation of an inner comet cloud during the lifetime of the cluster. Depending on the cluster density, most members of this comet cloud are concentrated at a few hundred to a few thousand astronomical units.