The Underexplored Frontier of Ice Giant Interiors and Dynamos

Krista Soderlund,Marius Millot,Yong-Jae Kim,Ravit Helled,Mandy Bethkenhagen,Jonathan Fortney,Sabine Stanley,Imke De Pater,Sebastien Hamel

doi:10.3847/25c2cfeb.5d65a2b0

Abstract

Whitepaper #233 submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032. Topics: giant planets systems; solar system formation, dynamics processes, and chronology; theory, computation, and modeling

Highlights

The interiors of Uranus and Neptune play a critical role in almost every aspect of their systems, ranging from bulk composition and heat flow to the dynamo and atmospheric dynamics to the configuration of the magnetosphere and potential resonant oscillations in the rings
Textbook models of the planets show a predominantly H/He convective envelope atop a thick water-dominated fluid convective mantle layer, with a rocky core. Models like these can be constructed that match either planet’s relatively poorly-known gravity field. Such models have never yielded adequate fits to the planetary heat flow governed by thermal evolution[9]
The degree to which winds in the visible atmosphere extend into the deeper interior has been a breakthrough discovery for Jupiter and Saturn in the past few years[19,20], and there is already some evidence for a quite dissimilar, shallower depth in Uranus and Neptune[21] which could be greatly refined

Summary

Introduction

The interiors of Uranus and Neptune play a critical role in almost every aspect of their systems, ranging from bulk composition and heat flow to the dynamo and atmospheric dynamics to the configuration of the magnetosphere and potential resonant oscillations in the rings. Bulk composition of the planets, especially noble gas abundances and isotopic ratios of H, C, N, S, and O, is key to how the giant planets formed and evolved[1]. The planetary dynamo was a high priority science objective of the Visions & Voyages Decadal Survey, and broader Interior science has become even more prioritized over the past decade. The discovery from the Kepler Mission of vast numbers of planets from 2 to 4 Earth radii[4], often called “mini-Neptunes”, gives additional impetus to understanding the interiors and dynamos of Uranus and Neptune

State of the Science