Magnetic Fields of Uranus and Neptune: Metallic Fluid Hydrogen

TL;DR

This paper investigates the magnetic fields of Uranus and Neptune, proposing they are generated mainly by metallic fluid hydrogen near their cores, with complex, non-dipolar magnetic structures due to their proximity to the surface.

Contribution

It introduces a new model suggesting metallic fluid hydrogen as the primary source of the planets' magnetic fields, based on high-pressure laboratory data.

Findings

Magnetic fields likely generated by metallic fluid hydrogen near the cores.

Non-dipolar magnetic fields expected due to proximity to the surface.

Ice cores are heterogeneous mixtures of multiple elements and compounds.

Abstract

The magnetic fields of the Ice Giant Planets Uranus and Neptune (U/N) are unique in the solar system. Based on a substantial database measured on Earth for representative planetary fluids at representative dynamic pressures up to 200 GPa (2 Mbar) and a few 1000 K, the complex magnetic fields of U/N are (i) probably made primarily by degenerate metallic fluid H (MFH) at or near the crossover from the H-He envelopes to Ice cores at ~100 GPa (Mbar) pressures and normalized radii of ~90% of the radii of U/N; (ii) because those magnetic fields are made relatively close to the surfaces of U/N, non-dipolar fields can be expected; (iii) the Ice cores are most probably a heterogeneous fluid mixture of H, N, O, C, Fe/Ni and silicate-oxides and their mutual reaction products at high pressures and temperatures,as discussed elsewhere. Ironically, there is probably little nebular Ice in the Ice Giant Planets.