While the vast majority of multiple-planet systems have their orbital angular momentum axes aligned 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 degrees with respect to 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 Jupiter masses. We also place a 95% upper limit of 0.80 m/s/yr on long-term trends caused by additional, more distant companions.
@article{arxiv.1608.03627,
title = {The Orbit and Mass of the Third Planet in the Kepler-56 System},
author = {Oderah Justin Otor and Benjamin T. Montet and John Asher Johnson and David Charbonneau and Andrew Collier-Cameron and Andrew W. Howard and Howard Isaacson and David W. Latham and Mercedes Lopez-Morales and Christophe Lovis and Michel Mayor and Giusi Micela and Emilio Molinari and Francesco Pepe and Giampaolo Piotto and David F. Phillips and Didier Queloz and Ken Rice and Dimitar Sasselov and Damien Ségransan and Alessandro Sozzetti and Stéphane Udry and Chris Watson},
journal= {arXiv preprint arXiv:1608.03627},
year = {2016}
}
Comments
7 pages, 1 figure, 2 tables; accepted for publication in AJ. Minor edits made after referee report