Using Jupiter's gravitational field to probe the Jovian convective dynamo.

Dali Kong,Keke Zhang,Gerald Schubert

doi:10.1038/srep23497

Abstract

Convective motion in the deep metallic hydrogen region of Jupiter is believed to generate its magnetic field, the strongest in the solar system. The amplitude, structure and depth of the convective motion are unknown. A promising way of probing the Jovian convective dynamo is to measure its effect on the external gravitational field, a task to be soon undertaken by the Juno spacecraft. We calculate the gravitational signature of non-axisymmetric convective motion in the Jovian metallic hydrogen region and show that with sufficiently accurate measurements it can reveal the nature of the deep convection.

Highlights

Jupiter possesses the strongest planetary magnetic field in the solar system, more than ten times larger than that of Earth1
The results reported in this paper have significant implications for interpreting any nonaxisymmetric gravitational field detected by Juno or some future Jupiter orbiter and for understanding the physics of the convection-driven
Our fully three-dimensional model of gravitational sounding provides a possible way of probing the Jovian convective dynamo as an inverse problem, by comparing its effect on the external gravitational field to non-axisymmetric gravitational measurements

Summary

Introduction

Jupiter possesses the strongest planetary magnetic field in the solar system, more than ten times larger than that of Earth. It is widely accepted that the Jovian magnetic field is generated by convection-driven motion in the deep metallic hydrogen region of the planet. The model is characterized by the depth H to the top of the dynamo region, the typical horizontal length scale L of the convection and its amplitude U0. It assumes that Jupiter is isolated, rotates rapidly about the symmetry axis, and consists of a compressible barotropic fluid (a polytrope of index unity) whose density is a function only of pressure. The Jovian magnetic field is generated by a parameterized convection with amplitude U0 and horizontal length scale L in the metallic hydrogen region. Additional model details can be found in the Methods section

Methods

Results

Conclusion