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Formation of Outer Planets: OverviewAn overview of current theories of planetary formation, with emphasis on giant planets is presented. The most detailed models are based upon observation of our own Solar System and of young stars and their environments. Terrestrial planets are believe to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk disspates. The primary questions regarding the core instability model is whether planets with small cores can accrete gaseous enveloples within the lifetimes of gaseous protoplanetary disks. The main alternative giant planet formation model is the disk instability model, in which gaseous planets form directly via gravitational instabilities within protoplanetary disks. Formation of giant planets via gas instability has never been demonstrated for realistic disk conditions. Moreover, this model has difficulty explaining the supersolar abundances of heavy elements in Jupiter and Saturn, and it does not explain the orgin of planets like Uranus and Neptune.
Document ID
20040043667
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Lissauer, Jack
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Astronomy
Meeting Information
Meeting: A Comparative Study of the Outer Planets Before the Exploration of Saturn by Cassini-Huygens
Location: Bern
Country: Switzerland
Start Date: January 12, 2004
End Date: January 17, 2004
Sponsors: ISSI
Funding Number(s)
OTHER: 344-30-50-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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