Mon. Not. R. Astron. Soc., 441, 442-451 (2014/June-2)
The 55 Cancri planetary system: fully self-consistent N-body constraints and a dynamical analysis.
NELSON B.E., FORD E.B., WRIGHT J.T., FISCHER D.A., VON BRAUN K., HOWARD A.W., PAYNE M.J. and DINDAR S.
Abstract (from CDS):
We present an updated study of the planets known to orbit 55 Cancri A using 1 418 high-precision radial velocity observations from four observatories (Lick, Keck, Hobby-Eberly Telescope, Harlan J. Smith Telescope) and transit time/durations for the inner-most planet, 55 Cancri `e' (Winn et al.). We provide the first posterior sample for the masses and orbital parameters based on self-consistent N-body orbital solutions for the 55 Cancri planets, all of which are dynamically stable (for at least 108 yr). We apply a GPU version of Radial velocity Using N-body Differential evolution Markov Chain Monte Carlo (run dmc; Nelson, Ford & Payne) to perform a Bayesian analysis of the radial velocity and transit observations. Each of the planets in this remarkable system has unique characteristics. Our investigation of high-cadence radial velocities and priors based on space-based photometry yields an updated mass estimate for planet `e' (8.09±0.26 M⊕), which affects its density (5.51±^1.32_1.00 g/cm3) and inferred bulk composition. Dynamical stability dictates that the orbital plane of planet `e' must be aligned to within 60° of the orbital plane of the outer planets (which we assume to be coplanar). The mutual interactions between the planets `b' and `c' may develop an apsidal lock about 180°. We find 36-45 per cent of all our model systems librate about the anti-aligned configuration with an amplitude of 51^○±^6^○_10^○. Other cases showed short-term perturbations in the libration of πb - πc, circulation, and nodding, but we find the planets are not in a 3:1 mean-motion resonance. A revised orbital period and eccentricity for planet `d' pushes it further towards the closest known Jupiter analogue in the exoplanet population.
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)
methods: statistical - techniques: radial velocities - planets and satellites: dynamical evolution and stability
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