  Hydrogen-helium mixtures at conditions of Jupiter's interior are studied with
first-principles computer simulations. The resulting equation of state (EOS)
implies that Jupiter possesses a central core of 14-18 Earth masses of heavier
elements, a result that supports core accretion as standard model for the
formation of hydrogen-rich giant planets. Our nominal model has about 2 Earth
masses of planetary ices in the H-He-rich mantle, a result that is, within
modeling errors, consistent with abundances measured by the 1995 Galileo Entry
Probe mission (equivalent to about 5 Earth masses of planetary ices when
extrapolated to the mantle), suggesting that the composition found by the probe
may be representative of the entire planet. Interior models derived from this
first-principles EOS do not give a match to Jupiter's gravity moment J4 unless
one invokes interior differential rotation, implying that jovian interior
dynamics has an observable effect on the measured gravity field.
