Precise transit and radial-velocity characterization of a resonant pair: The warm Jupiter TOI-216c and eccentric warm Neptune TOI-216b

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Authors

  • Rebekah I. Dawson
  • Chelsea X. Huang
  • Rafael Brahm
  • Karen A. Collins
  • Melissa J. Hobson
  • Andrés Jordán
  • Jiayin Dong
  • Judith Korth
  • Trifon Trifonov
  • Lyu Abe
  • Abdelkrim Agabi
  • Ivan Bruni
  • R. Paul Butler
  • Mauro Barbieri
  • Kevin I. Collins
  • Dennis M. Conti
  • Jeffrey D. Crane
  • Nicolas Crouzet
  • Phil Evans
  • Néstor Espinoza
  • Tianjun Gan
  • Tristan Guillot
  • Thomas Henning
  • Jack J. Lissauer
  • Eric L. N. Jensen
  • Wenceslas Marie Sainte
  • Djamel Mékarnia
  • Gordon Myers
  • Sangeetha Nandakumar
  • Howard M. Relles
  • Paula Sarkis
  • Pascal Torres
  • Stephen Shectman
  • François-Xavier Schmider
  • Avi Shporer
  • Chris Stockdale
  • Johanna Teske
  • Sharon Xuesong Wang
  • Carl Ziegler
  • G. Ricker
  • R. Vanderspek
  • David W. Latham
  • S. Seager
  • J. Winn
  • Jon M. Jenkins
  • L. G. Bouma
  • Jennifer A. Burt
  • David Charbonneau
  • Alan M. Levine
  • Scott McDermott
  • Brian McLean
  • Mark E. Rose
  • Andrew Vanderburg
  • Bill Wohler

Colleges, School and Institutes

Abstract

TOI-216 hosts a pair of warm, large exoplanets discovered by the TESS mission. These planets were found to be in or near the 2:1 resonance, and both of them exhibit transit timing variations (TTVs). Precise characterization of the planets’ masses and radii, orbital properties, and resonant behavior can test theories for the origins of planets orbiting close to their stars. Previous characterization of the system using the first six sectors of TESS data suffered from a degeneracy between planet mass and orbital eccentricity. Radial-velocity measurements using HARPS, FEROS, and the Planet Finder Spectrograph break that degeneracy, and an expanded TTV baseline from TESS and an ongoing ground-based transit observing campaign increase the precision of the mass and eccentricity measurements. We determine that TOI-216c is a warm Jupiter, TOI-216b is an eccentric warm Neptune, and that they librate in 2:1 resonance with a moderate libration amplitude of 60 - + 2 2 deg, a small but significant free eccentricity of 0.0222 - + 0.0003 0.0005 for TOI-216b, and a small but significant mutual inclination of 1°.2–3°.9 (95% confidence interval). The libration amplitude, free eccentricity, and mutual inclination imply a disturbance of TOI-216b before or after resonance capture, perhaps by an undetected third planet.

Details

Original languageEnglish
Article numberabd8d0
JournalThe Astronomical Journal
Volume161
Issue number4
Publication statusPublished - 4 Mar 2021

Keywords

  • exoplanet astronomy, exoplanet dynamics, transit timing variation method, radial velocity