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A scaling law for accretion zone sizesCurrent theories of runaway planetary accretion require small random velocities of the accreted particles. Two body gravitational accretion cross sections which ignore tidal perturbations of the Sun are not valid for the slow encounters which occur at low relative velocities. Wetherill and Cox have studied accretion cross sections for rocky protoplanets orbiting at 1 AU. Using analytic methods based on Hill's lunar theory, one can scale these results for protoplanets that occupy the same fraction of their Hill sphere as does a rocky body at 1 AU. Generalization to bodies of different sizes is achieved here by numerical integrations of the three-body problem. Starting at initial positions far from the accreting body, test particles are allowed to encounter the body once, and the cross section is computed. A power law is found relating the cross section to the radius of the accreting body (of fixed mass).
Document ID
19870013952
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Greenzweig, Yuval (California Univ. Santa Barbara, CA, United States)
Lissauer, Jack J. (California Univ. Santa Barbara, CA, United States)
Date Acquired
September 5, 2013
Publication Date
May 1, 1987
Publication Information
Publication: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986
Subject Category
Astrophysics
Accession Number
87N23385
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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