The Primordial Entropy of Jupiter

TL;DR

This paper investigates Jupiter's primordial entropy through formation simulations, revealing that non-convective interior regions are common and that formation parameters significantly influence its initial luminosity and entropy gradients.

Contribution

It introduces detailed formation models to quantify Jupiter's initial entropy and luminosity, emphasizing the importance of accretion rates and entropy gradients in early planetary evolution.

Findings

Proto-Jupiter often has non-convective interior regions.

Post-formation luminosity varies by a factor of 2-3 based on model parameters.

Entropy gradients can persist for about 10 million years after formation.

Abstract

The formation history of giant planets determines their primordial structure and consequent evolution. We simulate various formation paths of Jupiter to determine its primordial entropy, and find that a common outcome is for proto-Jupiter to have non-convective regions in its interior. We use planet formation models to calculate how the entropy and post-formation luminosity depend on model properties such as the solid accretion rate and opacity, and show that the gas accretion rate and its time evolution play a key role in determining the entropy profile. The predicted luminosity of Jupiter shortly after formation varies by a factor of $2$--$3$ for different choices of model parameters. We find that entropy gradients inside Jupiter persist for $\sim 10\ {\rm Myr}$ after formation. We suggest that these gradients should be considered together with heavy-element composition gradients when modeling Jupiter's evolution and internal structure.