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

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 \cite{2016Sato} (hereafter: S16), or are moving on mutually retrograde orbits. Here we examine the orbital stability of the system presented in S16 using the $n$-body code {\sc 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 re-analysis of the available observational data for the HD 47366 system, through the Levenberg-Marquardt technique and confirmed by MCMC Bayesian methodology. Our re-analysis 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.

arXiv comment12 pages, 12 figures, 5 tables, accepted for publication in AJ

References in corpus (46)

• emcee: The MCMC Hammer
• Validation of the new Hipparcos reduction
• The WASP Project and the SuperWASP Cameras
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey
• The Kilodegree Extremely Little Telescope (KELT): A Small Robotic Telescope for Large-Area Synoptic Surveys
• Retired A Stars and Their Companions: Exoplanets Orbiting Three Intermediate-Mass Subgiants
• Precise Radial Velocities of Giant Stars VII. Occurrence Rate of Giant Extrasolar Planets as a Function of Mass and Metallicity
• Foretellings of Ragnarök: World-engulfing Asymptotic Giants and the Inheritance of White Dwarfs
• Architecture of Planetary Systems Based on Kepler Data: Number of Planets and Coplanarity
• Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on The Entire 48 Month Dataset (Q1-Q17 DR24)
• Retired A Stars and Their Companions. III. Comparing the Mass-Period Distributions of Planets Around A-Type Stars and Sun-Like Stars
• System description and first light-curves of HAT, an autonomous observatory for variability search
• Systemic: A Testbed For Characterizing the Detection of Extrasolar Planets. I. The Systemic Console Package
• Retired A Stars and Their Companions: Eighteen New Jovian Planets
• Long-term evolution of three-planet systems to the post-Main Sequence and beyond
• The Twenty-Five Year Lick Planet Search
• A dynamical analysis of the proposed HU Aquarii planetary system
• An Activity Catalogue of Southern Stars
• On the dynamical stability of the proposed planetary system orbiting NSVS 14256825
• A Detailed Dynamical Investigation of the Proposed QS Virginis Planetary System
• The SEEDS Direct Imaging Survey for Planets and Scattered Dust Emission in Debris Disk Systems
• Application of the MEGNO technique to the dynamics of Jovian irregular satellites
• Multiple mean motion resonances in the HR 8799 planetary system
• A Dynamical Analysis of the Proposed Circumbinary HW Virginis Planetary System
• Revisiting the proposed planetary system orbiting the eclipsing polar HU Aquarii
• Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars
• A Double Planetary System around the Evolved Intermediate-Mass Star HD 4732
• A Detailed Analysis of the HD 73526 2:1 Resonant Planetary System
• Main-sequence progenitor configurations of the NN Ser candidate circumbinary planetary system are dynamically unstable
• The long-term stability of extrasolar system HD 37124. Numerical study of resonance effects
• Near 3:2 and 2:1 mean motion resonances formation in the systems observed by Kepler
• Resonances Required: Dynamical Analysis of the 24 Sex and HD 200964 Planetary Systems
• The Pan-Pacific Planet Search VII: The most eccentric planet orbiting a giant star
• Combining direct imaging and radial velocity data towards a full exploration of the giant planet population
• The Pan-Pacific Planet Search. IV. Two super-Jupiters in a 3:5 resonance orbiting the giant star HD33844
• The Pan-Pacific Planet Search VI: Giant planets orbiting HD 86950 and HD 222076
• The Anglo-Australian Planet Search XXV: A Candidate Massive Saturn Analog Orbiting HD 30177
• High Contrast Imaging with Spitzer : Constraining the Frequency of Giant Planets out to 1000 AU separations
• A Dynamical Investigation of the Proposed BD +20 2457 System
• The Dynamical History of Chariklo and its Rings
• A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
• The Pan-Pacific Planet Search V. Fundamental Parameters for 164 Evolved Stars
• Modelling the Inner Debris Disc of HR 8799
• A Possible Substellar Companion to the Intermediate-mass Giant HD 175679
• An Orbital Stability Study of the Proposed Companions of SW Lyncis

Cited by in corpus (5)

• Two Jovian planets around the giant star HD202696. A growing population of packed massive planetary pairs around massive stars?
• A Pair of Planets Likely in Mean-motion Resonance From Gravitational Microlensing
• Measuring the Orbital Parameters of Radial Velocity Systems in Mean Motion Resonance---a Case Study of HD 200964
• Stability analysis of three exoplanet systems
• 3D models of the circumstellar environments of evolved stars: Formation of multiple spiral structures