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The origin of comets among the accreting outer planets

Published online by Cambridge University Press:  12 April 2016

Richard Greenberg*
Affiliation:
Planetary Science Institute, 2030 E. Speedway, Suite 201, Tucson, Arizona 85719, USA

Abstract

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The hypothesis of formation of comets as an accompaniment to formation of Uranus and Neptune from icy planetesimals is attractive for several reasons, but has suffered from long-standing problems regarding formation of the planets themselves. The history of this problem is reviewed, and recent results are described that may help solve it. Numerical simulations of planet growth show that when the system of planetesimals is no longer artificially constrained to a power-law size distribution, growth of planets may occur in reasonable time. An adeguate number of comet-sized bodies to populate the Oort cloud is not produced as collisional debris during the planet-building process. Rather, the comets are probably a remnant of the original planetesimal “building blocks” from which the planets grew.

Type
Section I. Origin of Comets
Copyright
Copyright © Cambridge University Press 1985

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