Near-circular Orbits for Planets Around M/K-type Stars With Earth-like Sizes and Instellations

Recent advances have enabled the discovery of a population of potentially Earth-like planets, yet their orbital eccentricity, which governs their climate and provides clues about their origin and dynamical history, is still largely unconstrained.

We identify a sample of 17 transiting exoplanets around late-type stars with similar radii and irradiation to that of Earth and use the “photoeccentric effect” – which exploits transit durations – to infer their eccentricity distribution via hierarchical Bayesian modelling.

Our analysis establishes that these worlds further resemble Earth in that their eccentricities are nearly circular (mean eccentricity =0.060+0.040−0.028 and ≤0.15), with the exception of one outlier of moderate eccentricity. The results hint at a subset population of dynamically warmer Earths, but this requires a larger sample to statistically confirm.

The planets in our sample are thus largely subject to minimal eccentricity-induced seasonal variability and are consistent with emerging via smooth disk migration rather than violent planet-planet scattering.

David Kipping, Diana Solano-Oropeza, Daniel A. Yahalomi, Madison Li, Avishi Poddar, Xunhe Zhang

Comments: To appear in Nature Astronomy
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2501.10571 [astro-ph.EP] (or arXiv:2501.10571v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2501.10571
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Submission history
From: David Kipping
[v1] Fri, 17 Jan 2025 22:00:13 UTC (30,681 KB)
https://arxiv.org/abs/2501.10571
Astrobiology,