TOI-216b and TOI-216 c : two warm, large exoplanets in or slightly wide of the 2:1 orbital resonance
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Warm, large exoplanets with 10–100 day orbital periods pose a major challenge to our understanding of how planetary systems form and evolve. Although high eccentricity tidal migration has been invoked to explain their proximity to their host stars, a handful reside in or near orbital resonance with nearby planets, suggesting a gentler history of in situ formation or disk migration. Here we confirm and characterize a pair of warm, large exoplanets discovered by the TESS Mission orbiting K-dwarf TOI-216. Our analysis includes additional transits and transit exclusion windows observed via ground-based follow-up. We find two families of solutions, one corresponding to a sub-Saturn-mass planet accompanied by a Neptune-mass planet and the other to a Jupiter in resonance with a sub-Saturn-mass planet. We prefer the second solution based on the orbital period ratio, the planet radii, the lower free eccentricities, and libration of the 2:1 resonant argument, but cannot rule out the first. The free eccentricities and mutual inclination are compatible with stirring by other, undetected planets in the system, particularly for the second solution. We discuss prospects for better constraints on the planets' properties and orbits through follow-up, including transits observed from the ground.
Dawson , R I , Huang , C X , Lissauer , J J , Collins , K A , Sha , L , Armstrong , J , Conti , D M , Collins , K I , Evans , P , Gan , T , Horne , K , Ireland , M , Murgas , F , Myers , G , Relles , H M , Sefako , R , Shporer , A , Stockdale , C , Zerjal , M , Zhou , G , Ricker , G , Vanderspek , R , Latham , D W , Seager , S , Winn , J , Jenkins , J M , Bouma , L G , Caldwell , D A , Daylan , T , Doty , J P , Dynes , S , Esquerdo , G A , Rose , M , Smith , J C & Yu , L 2019 , ' TOI-216b and TOI-216 c : two warm, large exoplanets in or slightly wide of the 2:1 orbital resonance ' , Astronomical Journal , vol. 158 , no. 2 , 65 . https://doi.org/10.3847/1538-3881/ab24ba
Copyright © 2019. The American Astronomical Society. All rights reserved. This is the final published version of the work, which was originally published at: https://doi.org/10.3847/1538-3881/ab24ba
DescriptionK.H. acknowledges support from STFC grant ST/R00824/1.
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