Constraining the Planetary Obliquity Distribution of Warm Jupiters
Abstract
Warm Jupiters are an intriguing class of planets with uncertain origins. Their planetary obliquities could help distinguish between different formation pathways: planet-planet scattering and migration across resonances can excite large obliquities, whereas in-situ formation would more naturally produce low obliquities. We searched for oblateness-related anomalies in the transit light curves of six observationally favorable warm Jupiters: TOI-201b, TOI-1670c, TOI-199b, Kepler-9c, Kepler-30c, and Kepler-553c. Each planet's light curve is consistent with a spherical planet and provides degenerate constraints on the planet's sky-projected oblateness and obliquity. To overcome these limitations, we performed hierarchical Bayesian modeling of the population-level obliquity distribution. Assuming warm Jupiters are as oblate as Saturn (f ≈ 0.1), we find their median obliquity to be below 12∘ with $90$% confidence and below Saturn's obliquity (27∘) with $93$% confidence. Jupiter-like oblateness (f ≈ 0.06) and larger obliquities are allowed. Simulations of JWST observations predict that significantly tighter constraints can be derived.
Related
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BibTeX
@misc{lammers2026constraining,
title = {{Constraining the Planetary Obliquity Distribution of Warm Jupiters}},
author = {Caleb Lammers and Joshua N. Winn},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.01599},
eprint = {2609.01599},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.01599},
}
RIS
TY - UNPB
TI - Constraining the Planetary Obliquity Distribution of Warm Jupiters
AU - Caleb Lammers
AU - Joshua N. Winn
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.01599
UR - https://arxiv.org/abs/2609.01599
AB - Warm Jupiters are an intriguing class of planets with uncertain origins. Their planetary obliquities could help distinguish between different formation pathways: planet-planet scattering and migration across resonances can excite large obliquities, whereas in-situ formation would more naturally produce low obliquities. We searched for oblateness-related anomalies in the transit light curves of six observationally favorable warm Jupiters: TOI-201b, TOI-1670c, TOI-199b, Kepler-9c, Kepler-30c, and Kepler-553c. Each planet's light curve is consistent with a spherical planet and provides degenerate constraints on the planet's sky-projected oblateness and obliquity. To overcome these limitations, we performed hierarchical Bayesian modeling of the population-level obliquity distribution. Assuming warm Jupiters are as oblate as Saturn (f ≈ 0.1), we find their median obliquity to be below 12^∘ with $90$% confidence and below Saturn's obliquity (27^∘) with $93$% confidence. Jupiter-like oblateness (f ≈ 0.06) and larger obliquities are allowed. Simulations of JWST observations predict that significantly tighter constraints can be derived.
ER -