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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

References

Bailey, M.E. 1983a. The structure and evolution of the solar system comet cloud. Mon. Not. Roy. Astron. Soc., 204, 603–633.CrossRefGoogle Scholar
Bailey, M.E. 1983b. Comets, planet X, and the orbit of Neptune. Nature, 302, 399–400.CrossRefGoogle Scholar
Bailey, M.E. 1983c. Theories of cometary origin and the brightness of the infrared sky. Mon. Not. Roy. Astron. Soc., 205, 47P–52P.CrossRefGoogle Scholar
Cameron, A.G.W. 1978. The primitive solar accretion disc and the formation of the planets. In The Origin of the Solar System, ed. Dermott, S.F., John Wiley & Sons, New York, pp. 49–75.Google Scholar
Clarke, R.N., and Lucey, P.G. 1984. Spectral properties of ice-particulate mixtures: Implications for remote sensing I: Intimate mixtures. J. Geophys. Res., 89, 6341–6348.CrossRefGoogle Scholar
Clube, S.V.M., and Napier, W.M. 1982. Spiral arms, comets, and terrestrial catastrophism. Quart. J. Roy. Astron. Soc., 23, 45–66.Google Scholar
Clube, S.V.M., and Napier, W.M. 1984. Comet capture from molecular clouds: A dynamical constraint on star and planet formation. Mon. Not. Roy. Astron. Soc., 208, 575–588.Google Scholar
Davis, M., Hut, P., and Muller, R.A. 1984. Extinction of species by periodic comet showers. Nature, 308, 715–717.Google Scholar
Delsemme, A.H., and Rud, D.A. 1973. Albedos and cross-sections for the nuclei of comets 1969IX, 1970II, and 19711. Astron. & Astrophys., 28, 1–6.Google Scholar
Fernandez, J.A. 1980. On the existence of a comet belt beyond Neptune. Mon. Not. Roy. Astron. Soc., 192, 481–491.CrossRefGoogle Scholar
Fernandez, J.A. 1982. Dynamical aspects of the origin of comets. Astron. J., 87, 1318–1332.CrossRefGoogle Scholar
Hills, J.G. 1981. Comet showers and the steady state infall of comets from the Oort cloud. Astron. J., 86, 1730–1740.Google Scholar
Kresak, L., and Pittch, E.M. 1978. The intrinsic number density of active long-period comets in the inner solar system. Bull. Astron. Inst. Czech. 29, 299–309.Google Scholar
Low, F.J., et al. 1984. Infrared cirrus: New components of the extended IR emission. Astrophys. J., 278, L19–L22.CrossRefGoogle Scholar
Oort, J.H. 1950. The structure of the cometary cloud surrounding the solar system and a hypothesis concerning its origin. Bull. Astron. Inst. Neth., 11, 91–110.Google Scholar
Shoemaker, E.M., and Wolfe, R.F. 1984. Evolution of the Uranus-Neptune planetesimal swarm (abstract). In Lunar and Planetary Science XV, 780–781.Google Scholar
Weissman, P.R. 1980. Stellar peturbations of the cometary cloud. Nature, 288, 242–243.CrossRefGoogle Scholar
Weissman, P.R. 1982. Dynamical history of the Oort cloud. In Comets, ed. Wilkening, L.L., Univ. Arizona Press, Tucson, pp. 637–658.Google Scholar
Weissman, P.R. 1983. The mass of the Oort cloud. Astron. & Astrophys., 118, 90–94.Google Scholar
Weissman, P.R. 1984. The Vega particulate shell: Comets or asteroids? Science, 224, 987–989.CrossRefGoogle ScholarPubMed
Whipple, F.L. 1964. Evidence for a comet belt beyond Neptune. Proc. Natl. Acad. Sci., 51, 711–718.CrossRefGoogle ScholarPubMed
Whitmire, D.P., and Jackson, A.A. IV. 1984. Are periodic mass extinctions driven by a distant solar companion? Nature, 308, 713–715.Google Scholar