Hydromagnetic dynamo in the cores of Uranus and Neptune

Abstract

The explanation of the origin of a magnetic field of Uranus is difficult because the structure of the planet's interior is not well known and the strong thermal flux, which is associated with the operation of hydromagnetic dynamos in Jupiter and Saturn, seems to be absent or very low. We show here that the composition, physical state and electrical conductivity of the planet's core permits the generation of a magnetic field within the very low observational limits of its heat emission. We also suggest that the higher density and higher pressures in the core of Neptune could explain the suspected absence of a measurable field on that planet even though it is a relatively strong source of heat.