On the dynamical state of the HD 82943 Planetary System

Abstract

Previous analysis of radial velocity data of the star HD 82943 has shown that it hosts a pair of planets that are likely in 2:1 mean-motion resonance, with the orbital periods about 220 and 440 days (Lee et al. 2006). However, alternative fits that are qualitatively different have also been suggested, with the two planets in 1:1 resonance or the addition of a third planet possibly in a Laplace resonance with the other two (Gozdziewski & Konacki 2006; Beaugé et al. 2008). We present a new analysis of the HD 82943 system based on 10 years of radial velocity measurements obtained with the Keck telescope. An efficient and reliable method to explore the parameter space is needed because of the large number of model parameters and the cost of orbital integrations. We compare the results obtained using different approaches: multiple-Keplerian or N-body fitting, combined with the least-squares method on parameter grids or the Markov chain Monte Carlo method. A systematic exploration of the parameter space that combines statistical and dynamical analysis is performed to assess the viability of the different types of fits for the HD 82943 system.