Characterizing the Orbital and Dynamical State of the HD 82943 Planetary System with Keck Radial Velocity Data

Creators: Tan, Xianyu; Payne, Matthew J.; Lee, Man Hoi; Ford, Eric B.; Howard, Andrew W.; Johnson, John A.; Marcy, Geoff W.; Wright, Jason T.

Abstract

We present an updated analysis of radial velocity data of the HD 82943 planetary system based on 10 yr of measurements obtained with the Keck telescope. Previous studies have shown that the HD 82943 system has two planets that are likely in 2:1 mean-motion resonance (MMR), with orbital periods about 220 and 440 days. However, alternative fits that are qualitatively different have also been suggested, with two planets in a 1:1 resonance or three planets in a Laplace 4:2:1 resonance. Here we use χ^2 minimization combined with a parameter grid search to investigate the orbital parameters and dynamical states of the qualitatively different types of fits, and we compare the results to those obtained with the differential evolution Markov chain Monte Carlo method. Our results support the coplanar 2:1 MMR configuration for the HD 82943 system, and show no evidence for either the 1:1 or three-planet Laplace resonance fits. The inclination of the system with respect to the sky plane is well constrained at 20^(+4.9)_(-5.5) degrees, and the system contains two planets with masses of about 4.78 M_J and 4.80 M_J (where M_J is the mass of Jupiter) and orbital periods of about 219 and 442 days for the inner and outer planet, respectively. The best fit is dynamically stable with both eccentricity-type resonant angles θ_1 and θ_2 librating around 0°.

Additional Information

© 2013 American Astronomical Society. Received 2013 May 27; accepted 2013 September 3; published 2013 October 18. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. We thank NASA and NExScI for providing Keck time in the 2011A semester for the study of multiplanet systems (NExScI ID40/Keck ID# N141Hr). Data presented herein were obtained at the W.M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We thank Howard Isaacson, R.P. Butler, and S. Vogt for help with observing at the telescope, and the referee for helpful comments on the manuscript. X.T. and M.H.L. were supported in part by the Hong Kong RGC grant HKU 7034/09P. Contributions by M.J.P. and E.B.F. were supported by NASA Origins of Solar Systems grant NNX09AB35G prior to 2011 August 8. J.A.J. was supported by generous grants from the David and Lucile Packard Foundation and the Alfred P. Sloan Foundation. J.T.W. was supported by NSF Astronomy and Astrophysics grant AST-1211441. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. M.H.L. and E.B.F. also acknowledge the hospitality of the Isaac Newton Institute for Mathematical Sciences, where part of this work was completed.

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