Structure and evolution of Uranus and Neptune
We present three-layer interior models of Uranus and Neptune with central rocky cores, mantles of water, methane, and ammonia (the 'ices'), and outer envelopes primarily composed of hydrogen and helium. The models incorporate a new H/sub 2/O equation of state based on experimental data which is considerably 'softer' than previous H/sub 2/O equations of state. Corrections for interior temperature approx.5000 /sup 0/K are included in the models, and the thermal evolution of both planets is investigated using recent heat flow measurements. We find that evolutionary considerations are consistent with gravitational field data in supporting models with approximately solar abundances of 'ice' and 'rock.' Models with very low abundances of water, methane, and ammonia can be excluded. Evolutionary considerations indicate that initial temperatures and luminosities for Uranus and Neptune were not substantially higher than the present value. Both planets apparently have relatively small (approx.1--2 earth masses) hydrogen-helium envelopes, with Neptune's envelope smaller than Uranus'. A monotonic trend is evident among the Jovian planets: all have central rock-ice cores of approx.15 earth masses, but with hydrogen-helium envelopes which decrease in mass from Jupiter to Saturn to Uranus to Neptune.
- Research Organization:
- Department of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721
- OSTI ID:
- 5449912
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 85:B1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
NEPTUNE PLANET
GEOLOGIC MODELS
PLANETARY EVOLUTION
URANUS PLANET
AMMONIA
EQUATIONS OF STATE
GEOLOGIC HISTORY
HEAT FLOW
HELIUM
HYDROGEN
ICE
METHANE
WATER
ALKANES
CRYOGENIC FLUIDS
ELEMENTS
EQUATIONS
FLUIDS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PLANETS
RARE GASES
SOLAR SYSTEM EVOLUTION
640107* - Astrophysics & Cosmology- Planetary Phenomena