The Change in Jupiter's Moment of Inertia due to Core Erosion and Planetary Contraction

TL;DR

This paper investigates how Jupiter's internal structure and evolution, including core erosion and planetary contraction, affect its moment of inertia over time, with implications for understanding its formation history.

Contribution

It presents a model showing how core erosion and contraction can significantly alter Jupiter's normalized moment of inertia during its evolution.

Findings

Jupiter's NMOI could have increased from ~0.235 to ~0.264 over time.

Low NMOI values are only present during the first million years of evolution.

Re-evaluation of dynamical models is needed for accurate primordial NMOI estimates.

Abstract

We explore the change in Jupiter's normalized axial moment of inertia (NMOI) assuming that Jupiter undergoes core erosion. It is found that Jupiter's contraction combined with an erosion of 20 M_Earth from a primordial core of 30 M_Earth can change Jupiter's NMOI over time significantly. It is shown that Jupiter's NMOI could have changed from ~0.235 to ~0.264 throughout its evolution. We find that a NMOI value of ~0.235 as suggested by dynamical models (Ward & Canup, 2006, ApJ, 640, L91) could, in principle, be consistent with Jupiter's primordial internal structure. Low NMOI values, however, persist only for the first ~ 10^6 years of Jupiter's evolution. Re-evaluation of dynamical stability models as well as more sophisticated evolution models of Jupiter with core erosion seem to be required in order to provide more robust estimates for Jupiter's primordial NMOI.