A Validated Low-to-Intermediate Mass Planetary Interior Structure Model and New Mass-Radius Relations

Fuente: arXiv
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Main Authors: Skinner, Bennett Neil, Pudritz, Ralph E., Cloutier, Ryan
Format: Preprint
Published: 2026
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author Skinner, Bennett Neil
Pudritz, Ralph E.
Cloutier, Ryan
author_facet Skinner, Bennett Neil
Pudritz, Ralph E.
Cloutier, Ryan
contents The increasing precision of planetary mass and radius observations is bringing major questions about the structure and formation of planets--such as the nature of the radius valley and origin of super-Mercuries--within reach, demanding the development of interior structure models with more physics to more accurately determine planetary radii for a given composition. Here, we present a new model that includes state-of-the-art equations of state following the latest experimental and computational results, a physically-motivated mineralogy allowing multiple species to coexist within planetary layers, a non-adiabatic temperature profile, melting, and other features. This model replicates Earth's radius and moment of inertia coefficient to within $0.2\%$, Mars and the Moon's to within $0.5\%$, and Mercury, Venus, and Europa's to within $1\%$ or 3$σ$. We use this model to calculate mass-radius relationships for H/He-enveloped, water-rich, Earth-like, and iron-rich bodies with masses between $0.01$--$100\, M_\oplus$. We calculate mass-radius tables and fit piece-wise power-laws to them for ${<}8M_\oplus$ planets, finding that the exponent in $M=bR^a$ increases with mass and core mass fraction. We find radii generally smaller than in literature mass-radius relations at low instellations and larger at high instellations, with our improvement on the literature comparable to observational uncertainties. State-of-the-art interior structure models are thus required to interpret observational data. Our mass-radius curves comprising 32,975 model planets are publicly available.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15304
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Validated Low-to-Intermediate Mass Planetary Interior Structure Model and New Mass-Radius Relations
Skinner, Bennett Neil
Pudritz, Ralph E.
Cloutier, Ryan
Earth and Planetary Astrophysics
The increasing precision of planetary mass and radius observations is bringing major questions about the structure and formation of planets--such as the nature of the radius valley and origin of super-Mercuries--within reach, demanding the development of interior structure models with more physics to more accurately determine planetary radii for a given composition. Here, we present a new model that includes state-of-the-art equations of state following the latest experimental and computational results, a physically-motivated mineralogy allowing multiple species to coexist within planetary layers, a non-adiabatic temperature profile, melting, and other features. This model replicates Earth's radius and moment of inertia coefficient to within $0.2\%$, Mars and the Moon's to within $0.5\%$, and Mercury, Venus, and Europa's to within $1\%$ or 3$σ$. We use this model to calculate mass-radius relationships for H/He-enveloped, water-rich, Earth-like, and iron-rich bodies with masses between $0.01$--$100\, M_\oplus$. We calculate mass-radius tables and fit piece-wise power-laws to them for ${<}8M_\oplus$ planets, finding that the exponent in $M=bR^a$ increases with mass and core mass fraction. We find radii generally smaller than in literature mass-radius relations at low instellations and larger at high instellations, with our improvement on the literature comparable to observational uncertainties. State-of-the-art interior structure models are thus required to interpret observational data. Our mass-radius curves comprising 32,975 model planets are publicly available.
title A Validated Low-to-Intermediate Mass Planetary Interior Structure Model and New Mass-Radius Relations
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2604.15304