Nonuniform viscosity in the solar nebula and large masses of Jupiter and Saturn

TL;DR

This paper proposes a theory that nonuniform viscosity in the solar nebula explains why Jupiter and Saturn are the largest planets with the most hydrogen and helium, addressing a longstanding puzzle in planetary formation.

Contribution

It introduces a novel model of nonuniform viscosity in the solar nebula that accounts for the mass distribution of giant planets and their gas content, contrasting with previous uniform viscosity models.

Findings

Nonuniform viscosity leads to faster outer nebula inflow and material accumulation at Jupiter-Saturn.

Jupiter and Saturn's large masses result from slower inflow allowing more gas capture.

The model explains the low mass of Mercury through viscosity effects.

Abstract

I report a novel theory that nonuniform viscous frictional force in the solar nebula accounts for the largest mass of Jupiter and Saturn and their largest amount of H and He among the planets, two outstanding facts that are unsolved puzzles in our understanding of origin of the Solar System. It is shown that the nebula model of uniform viscosity does not match the present planet masses. By studying current known viscosity mechanisms, I show that viscosity is more efficient in the inner region inside Mercury and the outer region outside Jupiter-Saturn than the intermediate region. The more efficient viscosity drives faster radial inflow of material during the nebula evolution. Because the inflow in the outer region is faster than the intermediate region, the material tends to accumulate in Jupiter-Saturn region which is between the outer and intermediate region. It is demonstrated that the gas trapping time of Jovian planets is longer than the inflow time in the outer region. Therefore the gas already flows to Jupiter-Saturn region before Uranus and Neptune can capture significant gas. But the inflow in the Jupiter-Saturn region is so slow that they can capture large amount of gas before the gas can flow further inward. Hence they have larger masses with larger H and He content than Uranus and Neptune. I also extend the discussion to the masses of the terrestrial planets, especially low mass of Mercury. The advantages of this theory are discussed.