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Dynamical evolution of the Oort cloud

Published online by Cambridge University Press:  12 April 2016

Paul R. Weissman
Paul R. Weissman*
Affiliation:
Earth and Space Sciences Division, Jet Propulsion Laboratory, Pasadena, CA 91109, USA

Abstract

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New studies of the dynamical evolution of cometary orbits in the Oort cloud are made using a revised version of Weissman’s (1982) Monte Carlo simulation model, which more accurately mimics the perturbation of comets by the giant planets. It is shown that perturbations by Saturn provide a substantial barrier to the diffusion of cometary perihelia into the inner solar system; Jupiter also. Perturbations by Uranus and Neptune are rarely great enough to remove comets from the Oort cloud, but do serve to scatter the comets in the cloud in 1/a. The new model gives a population of 1.8 to 2.1 × 1012 comets for the present-day Oort cloud, and a mass of 7 to 8 earth masses. Perturbation of the Oort cloud by giant molecular clouds in the galaxy is discussed, as is evidence for a massive “inner Oort cloud” internal to the observed one. The possibility of an unseen solar companion orbiting in the Oort cloud and causing periodic comet showers is shown to be dynamically plausible but unlikely based on the observed cratering rate on the earth and moon.

Type
Section II. The Oort Cloud of Comets
Information
International Astronomical Union Colloquium , Volume 83: Dynamics of Comets: Their Origin and Evolution , 1985 , pp. 87 - 96
Copyright
Copyright © Cambridge University Press 1985

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