The Eccentricity Distribution of Warm Sub-Saturns in TESS
Abstract
We present the eccentricity distribution of warm sub-Saturns (4-8 Re, 8-200 day periods) as derived from an analysis of transit light curves from NASA's Transiting Exoplanet Survey Satellite (TESS) mission. We use the "photoeccentric" effect to constrain the eccentricities of 76 planets, comprising 60 and 16 from single- and multi-transiting systems, respectively. We employ Hierarchical Bayesian Modelling to infer the eccentricity distribution of the population, testing both a Beta and Mixture Beta distribution. We identify a few highly eccentric (e ~ 0.7-0.8) warm sub-Saturns with eccentricities that appear too high to be explained by disk migration or planet-planet scattering alone, suggesting high-eccentricity migration may play a role in their formation. The majority of the population have a mean eccentricity of e = 0.103+0.047-0.045, consistent with both planet-disk and planet-planet interactions. Notably, we find that the highly eccentric sub-Saturns occur in single-transiting systems. This study presents the first evidence at the population level that the eccentricities of sub-Saturns may be sculpted by dynamical processes.
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Cite
@article{arxiv.2505.04106,
title = {The Eccentricity Distribution of Warm Sub-Saturns in TESS},
author = {Tyler R. Fairnington and Jiayin Dong and Chelsea X. Huang and Emma Nabbie and George Zhou and Duncan Wright and Karen A. Collins and Jon M. Jenkins and David W. Latham and George Ricker and Samuel N. Quinn and Sara Seager and Avi Shporer and Roland Vanderspek and Joshua N. Winn and Calvin Ajizian and Akihiko Fukui and David Baker and Giuseppe Conzo and Robert Scott Fisher and Raquel Forés-Toribio and Tianjun Gan and Alexey Garmash and Kai Ikuta and Adam Lark and Jerome P. de Leon and Katherine Linnenkohl and Christopher R. Mann and Owen Mitchem and Mayuko Mori and Jose A. Muñoz and Norio Narita and Adam Popowicz and Don Radford and Justus Randolph and Fabian Rodriguez Frustaglia and Richard P. Schwarz and Chris Stockdale and Jiaqi Wang and Noriharu Watanabe and Francis P. Wilkin and Krzysztof Sz. Zieliński and Emma Esparza-Borges and Felipe Murgas and Enric Pallé and Hannu Parviainen and Selçuk Yalçınkaya and Özgür Baştürk},
journal= {arXiv preprint arXiv:2505.04106},
year = {2025}
}
Comments
Accepted for publication in MNRAS