Re-analyzing the dynamical stability of the HD 47366 planetary system

Marshall, J. P. and Wittenmyer, R. A. and Horner, J. and Clark, J. and Mengel, M. W. and Hinse, T. C. and Agnew, M. T. and Kane, S. R. (2019) Re-analyzing the dynamical stability of the HD 47366 planetary system. The Astronomical Journal, 157 (1 - Article 1). ISSN 0004-6256

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Abstract

Multi-planet systems around evolved stars are of interest to trace the evolution of planetary systems into the post-main-sequence phase. HD 47366, an evolved intermediate-mass star, hosts two giant planets on moderately eccentric orbits. Previous analysis of the planetary system has revealed that it is dynamically unstable on timescales much shorter than the stellar age unless the planets are trapped in mutual 2:1 mean- motion resonance, inconsistent with the orbital solution presented in Sato et al., or are moving on mutually retrograde orbits. Here we examine the orbital stability of the system presented in S16 using the n-body code MERCURY over a broad range of a-e parameter space consistent with the observed radial velocities, assuming they are on co-planar orbits. Our analysis confirms that the system as proposed in S16 is not dynamically stable. We therefore undertake a thorough reanalysis of the available observational data for the HD 47366 system, through the Levenberg-Marquardt technique and confirmed by MCMC Bayesian methodology. Our reanalysis reveals an alternative, lower-eccentricity fit that is vastly preferred over the highly eccentric orbital solution obtained from the nominal best-fit presented in S16. The new, improved dynamical simulation solution reveals the reduced eccentricity of the planetary orbits, shifting the HD 47366 system into the edge of a broad stability region, increasing our confidence that the planets are all that they seem to be. Our rigorous examination of the dynamical stability of HD 47366 stands as a cautionary tale in finding the global best-fit model.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 10 Sep 2019 04:57
Last Modified: 25 Sep 2019 06:37
Uncontrolled Keywords: planetary systems; planets and satellites; dynamical evolution; stability; stars; HD 47366; astrophysics; planetary astrophysics
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.3847/1538-3881/aaef32
URI: http://eprints.usq.edu.au/id/eprint/36515

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