Interior Structure of Saturn Inferred from Pioneer 11 Gravity Data

The structure of Saturn is studied via a fourth-order theory for rotating planets and equations of state for the envelope which depend parametrically on the helium abundance, on the starting temperature for the adiabat, and on adopted forms of the pressure-density curve in the region of transition from molecular to metallic hydrogen. Models are constrained by the values of J2 and J4 obtained from the Pioneer-Saturn celestial mechanics experiment. Equations of state are tested by computing Jupiter models, which can now be subjected to a more stringent comparison with observed zonal harmonics. We find that Saturn has a low-density hydrogen-helium envelope with no evidence for enhancement of H2O, CH4, or other abundant compounds. Such compounds are presumably located near the core. The helium mass abundance for Saturn's envelope appears to be in the range of ∼0.12 to ∼0.19, but this result is very model-dependent. The helium abundance in the envelope of Jupiter is apparently very similar to that of Saturn.

[1]  G. F. Lindal,et al.  Structure of the Ionosphere and Atmosphere of Saturn from Pioneer 11 Saturn Radio Occultation , 1980 .

[2]  M. Desch,et al.  Voyager Detection of Nonthermal Radio Emission from Saturn , 1980, Science.

[3]  W. Hubbard.  Intrinsic luminosities of the Jovian planets , 1980 .

[4]  G. Null,et al.  Pioneer Saturn Celestial Mechanics Experiment , 1980, Science.

[5]  A. Ingersoll,et al.  Pioneer Saturn Infrared Radiometer: Preliminary Results , 1980, Science.

[6]  W. Hubbard,et al.  Structure and evolution of Uranus and Neptune , 1980 .

[7]  J. Armstrong,et al.  Interplanetary phase scintillation and the search for very low frequency gravitational radiation , 1979 .

[8]  W. Hubbard.  de Sitter's theory flattens Jupiter , 1977 .

[9]  W. Slattery.  The structure of the planets Jupiter and Saturn , 1976 .

[10]  G. W. Null,et al.  Gravity field of Jupiter and its satellite from Pioneer 10 and Pioneer 11 tracking data , 1976 .

[11]  W. Hubbard,et al.  Statistical mechanics of light elements at high pressure. IV - A model free energy for the metallic phase. [for Jovian type planet interiors] , 1976 .

[12]  D. Stevenson.  Thermodynamics and phase separation of dense fully ionized hydrogen-helium fluid mixtures , 1975 .

[13]  G. Orton.  The thermal structure of Jupiter I. Implications of Pioneer 10 infrared radiometer data , 1975 .

[14]  W. Hubbard,et al.  High zonal harmonics of rapidly rotating planets , 1975 .

[15]  M. Belton,et al.  The thermal structure of the atmosphere of Jupiter , 1974 .

[16]  W. Hubbard.  Inversion of gravity data for giant planets , 1974 .

[17]  R. Newburn,et al.  A survey of the outer planets Jupiter, Saturn, Uranus, Neptune, Pluto, and their satellites , 1973 .

[18]  W. Hubbard.  Thermal structure of Jupiter , 1968 .

[19]  E. Salpeter,et al.  Theoretical high-pressure equations of state including correlation energy. , 1967 .

[20]  R. A. James.  The Structure and Stability of Rotating Gas Masses. , 1964 .

[21]  J. Pollack,et al.  A calculation of Saturn's gravitational contraction history , 1977 .

[22]  W. Hubbard,et al.  Interior structure of Jupiter - Theory of gravity sounding , 1976 .

[23]  E. Salpeter,et al.  Interior models of Jupiter , 1976 .

[24]  J. Anderson,et al.  The gravity field of Jupiter , 1976 .

[25]  R. Smoluchowski.  Origin and structure of Jupiter and its satellites , 1976 .