The orbit and mass of the third planet in the Kepler-56 system

Oderah Justin Otor, Benjamin T. Montet, John Asher Johnson, David Charbonneau, Andrew Collier Cameron, Andrew W. Howard, Howard Isaacson, David W. Latham, Mercedes Lopez-Morales, Christophe Lovis, Michel Mayor, Giusi Micela, Emilio Molinari, Francesco Pepe, Giampaolo Piotto, David F. Phillips, Didier Queloz, Ken Rice, Dimitar Sasselov, Damien SégransanAlessandro Sozzetti, Stéphane Udry, Chris Watson

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While the vast majority of multiple-planet systems have orbital angular momentum axes that align with the spin axis of their host star, Kepler-56 is an exception: its two transiting planets are coplanar yet misaligned by at least 40° with respect to the rotation axis of their host star. Additional follow-up observations of Kepler-56 suggest the presence of a massive, non-transiting companion that may help explain this misalignment. We model the transit data along with Keck/HIRES and HARPS-N radial velocity data to update the masses of the two transiting planets and infer the physical properties of the third, non-transiting planet. We employ a Markov Chain Monte Carlo sampler to calculate the best-fitting orbital parameters and their uncertainties for each planet. We find the outer planet has a period of 1002 ± 5 days and minimum mass of 5.61 ± 0.38 MJup . We also place a 95% upper limit of 0.80 m s-1 yr-1 on long-term trends caused by additional, more distant companions.

Original languageEnglish
Article number165
Number of pages7
JournalAstronomical Journal
Issue number6
Publication statusPublished - 1 Dec 2016


  • Planets and satellites: fundamental parameters
  • Planets and satellites: individual (Kepler-56)
  • Techniques: radial velocities


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