Planetary Sciences American and Soviet Research/Proceedings from the U.S.-U.S.S.R. Workshop on Planetary Sciences (1991) / Chapter Skim
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12. Giant Planets and Their Satellites: What are the Relationships Between Their Properties and How They Formed?
12. Giant Planets and Their Satellites: What are the Relationships Between Their Properties and How They Formed?
Pages 163-173
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From page 163... ...
Indeed, Jupiter and Saturn exhibit evidence for rock and/or ice cores or central concentrations that probably accumulated first, acting as nuclei for subsequent gas accumulation. This is a "planetary" accumulation process, distinct from the stellar formation process, even though most of Jupiter has a similar composition to the primordial Sun.
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From page 164... ...
Planet X (a body beyond Pluto) has been frequently mentioned as a possibility, but no firm corroborative evidence currently exists.
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From page 165... ...
The outer radius of the solar nebula is not known, but was presumably determined by the angular momentum budget of the cloud from which the Sun and planets formed. INTERIOR MODELS One could say a lot about how giant planets formed if one knew their internal structures.
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From page 167... ...
ATMOSPHERIC COMPOSITIONS ANI) THEIR IMPLICATIONS Many of the minor constituents in giant planets undergo condensation (cloud formation)
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From page 168... ...
1987~. If we are to judge from known carbonaceous chondrites, then the amount of such material needed to create the observed Jovian or Saturnian carbon enrichment is very large, 20 to 30 Earth masses, especially when one considers that this must be assimilated material (not part of the unassimilated core)
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From page 169... ...
In this case, the gravitational energy of accretion created the primordial heat reservoir responsible for the current heat leakage. In Saturn, the heat flow is marginally consistent with the same interpretation, but the observed depletion of helium in the atmosphere requires a large gravitational energy release from the downward migration of helium droplets.
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From page 170... ...
The recent enthusiasm for an impact origin of the Earth's Moon suggests that the Uranian system deserves similar attention. Impact origin seems to make less sense for Jupiter and Saturn, where the target is mostly gas, even though these planets must also have had giant impacts.
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From page 171... ...
The lack of CO in Titan, and presumably Briton, may reflect the processing of solar nebula CO into CH4 in the disk or envelope surrounding the proto-giant planet, rather than any statement about solar nebula conditions. The only statement about temperature that seems reasonably firm is the placement of water condensation (T ~ 160 K)
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From page 172... ...
pointed out that if the surface density of solids is sufficiently high in the region of Jupiter formation then a runaway accretion may take place, forming the necessary Jupiter core in ~ 105 years. The onset of ice condensation helps increase the surface density by a factor of three, but this may not be sufficient by itself.
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From page 173... ...
1984. Planetary Interiors Van Nostrand Reinhold.
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