An Energy Perspective of Core Erosion in Gas Giant Planets

Fuente: arXiv
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Main Authors: Fuentes, J. R., Mankovich, Christopher R., Sur, Ankan
Format: Preprint
Published: 2025
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author Fuentes, J. R.
Mankovich, Christopher R.
Sur, Ankan
author_facet Fuentes, J. R.
Mankovich, Christopher R.
Sur, Ankan
contents Juno and Cassini have shown that Jupiter and Saturn likely contain extended gradients of heavy elements. Yet, how these gradients can survive over billions of years remains an open question. Classical convection theories predict rapid mixing and homogenization, which would erase such gradients on timescales far shorter than the planets' ages. To address this, we estimate the energy required to erode both dense and fuzzy cores, and compare it to what the planet can realistically supply. If the entire cooling budget is available to drive mixing, then even a compact core can, in principle, be destroyed. But if mixing is limited to the thermal energy near the core, which is another plausible scenario, the energy falls short. In that case, Jupiter can erode a fuzzy core by up to approximately $10~\mearth$, but a compact one remains intact. Saturn's core is more robust. Even in the fuzzy case, only about $1~\mearth$ is lost, and if the core is compact, erosion is negligible. The outcome depends sensitively on the assumed initial temperature and entropy profiles. Hotter and more superadiabatic interiors are more prone to mixing. We suggest that 3D simulations of convection driven from above, with realistic stratification and enough depth (i.e., many density scale heights) would be of great interest to further constrain the energy budget for core erosion.
format Preprint
id arxiv_https___arxiv_org_abs_2507_05109
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An Energy Perspective of Core Erosion in Gas Giant Planets
Fuentes, J. R.
Mankovich, Christopher R.
Sur, Ankan
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
Juno and Cassini have shown that Jupiter and Saturn likely contain extended gradients of heavy elements. Yet, how these gradients can survive over billions of years remains an open question. Classical convection theories predict rapid mixing and homogenization, which would erase such gradients on timescales far shorter than the planets' ages. To address this, we estimate the energy required to erode both dense and fuzzy cores, and compare it to what the planet can realistically supply. If the entire cooling budget is available to drive mixing, then even a compact core can, in principle, be destroyed. But if mixing is limited to the thermal energy near the core, which is another plausible scenario, the energy falls short. In that case, Jupiter can erode a fuzzy core by up to approximately $10~\mearth$, but a compact one remains intact. Saturn's core is more robust. Even in the fuzzy case, only about $1~\mearth$ is lost, and if the core is compact, erosion is negligible. The outcome depends sensitively on the assumed initial temperature and entropy profiles. Hotter and more superadiabatic interiors are more prone to mixing. We suggest that 3D simulations of convection driven from above, with realistic stratification and enough depth (i.e., many density scale heights) would be of great interest to further constrain the energy budget for core erosion.
title An Energy Perspective of Core Erosion in Gas Giant Planets
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2507.05109