Kavli Affiliate: Sara Seager
| First 5 Authors: Tyler R. Fairnington, Jiayin Dong, Chelsea X. Huang, Emma Nabbie, George Zhou
| Summary:
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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