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| Main Authors: | , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2507.02112 |
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| _version_ | 1866909816262230016 |
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| author | Huré, J. -M. Noé, P. Staelen, C. Di Folco, E. |
| author_facet | Huré, J. -M. Noé, P. Staelen, C. Di Folco, E. |
| contents | We have analyzed the effects of rotation on mass-radius relationships for single-layer and two-layer planets having a core and an envelope made of pure materials among iron, perovskite and water in solid phase. The numerical surveys use the DROP code updated with a modified polytropic equation-of-state (EOS) and investigate flattening parameters $f$ up to $0.2$. In the mass range $0.1 M_\oplus < M < 10 M_\oplus$, we find that rotation systematically shifts the curves of composition towards larger radii and/or smaller masses. Relative to the spherical case, the equatorial radius $R_{eq}$ is increased by about $0.36f$ for single-layer planets, and by $0.30f$ to $0.55f$ for two-layer planets (depending on the core size fraction $q$ and planet mass $M$). Rotation is an additional source of confusion in deriving planetary structures, as the radius alterations are of the same order as i) current observational uncertainties for super-Earths, and ii) EOS variations. We have established a multivariate fit of the form $R_{eq}(M,f,q)$, which enables a fast characterization of the core size and rotational state of rocky planets and ocean worlds. We discuss how the observational data must be shifted in the diagrams to self-consistently account for an eventual planet spin, depending on the geometry of the transit (circular/oblate). A simple application to the recently characterized super-Earth candidate LHS1140b is discussed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_02112 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Impact of rotation on synthetic mass-radius relationships of two-layer rocky planets and water worlds Huré, J. -M. Noé, P. Staelen, C. Di Folco, E. Earth and Planetary Astrophysics We have analyzed the effects of rotation on mass-radius relationships for single-layer and two-layer planets having a core and an envelope made of pure materials among iron, perovskite and water in solid phase. The numerical surveys use the DROP code updated with a modified polytropic equation-of-state (EOS) and investigate flattening parameters $f$ up to $0.2$. In the mass range $0.1 M_\oplus < M < 10 M_\oplus$, we find that rotation systematically shifts the curves of composition towards larger radii and/or smaller masses. Relative to the spherical case, the equatorial radius $R_{eq}$ is increased by about $0.36f$ for single-layer planets, and by $0.30f$ to $0.55f$ for two-layer planets (depending on the core size fraction $q$ and planet mass $M$). Rotation is an additional source of confusion in deriving planetary structures, as the radius alterations are of the same order as i) current observational uncertainties for super-Earths, and ii) EOS variations. We have established a multivariate fit of the form $R_{eq}(M,f,q)$, which enables a fast characterization of the core size and rotational state of rocky planets and ocean worlds. We discuss how the observational data must be shifted in the diagrams to self-consistently account for an eventual planet spin, depending on the geometry of the transit (circular/oblate). A simple application to the recently characterized super-Earth candidate LHS1140b is discussed. |
| title | Impact of rotation on synthetic mass-radius relationships of two-layer rocky planets and water worlds |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2507.02112 |