An Edge-On Orbit for the Eccentric Long-Period Planet HR 5183 b

Abstract

The long-period giant planet HR 5183 b has one of the most extreme orbits among exoplanets known to date, and represents a test for models of their dynamical evolution. In this work we use Hipparcos-Gaia astrometry to measure the orbital inclination of this planet for the first time and find $i=89.9_{-13.5}^{+13.3\circ }$, fully consistent with edge-on. The long orbital period and high eccentricity of HR 5183 b are supported by our results, with $P=102_{-34}^{+84}$ years and $e=0.87\pm 0.04$. We confirm that HR 5183 forms a physically bound binary with HIP 67291 at a projected separation of 15400 AU, and derive new constraints on the orbit of this pair. We combine these results to measure the mutual inclination between the planetary and binary orbits; we observe significant evidence for misalignment, which remains even after accounting for bias of the prior towards high mutual inclinations. However, our results are too imprecise to evaluate a recent prediction that the mutual inclination should reflect the formation history of HR 5183 b. Further observations, especially the release of the full Gaia astrometric data, will allow for improved constraints on the planet-binary mutual inclination. $52\pm 16\%$ of known planets with eccentricities $e\ge 0.8$ are found in multiple star systems, a rate that we find to be greater than for the overall planet population to moderate significance ($p=0.0075$). This supports the hypothesis that dynamical interactions with wide stellar companions plays an important role in the formation of highly eccentric exoplanets.

16 pages, 8 figures, 6 tables. Published in MNRAS. Significant revisions compared to version 1

References in corpus (40)

• The Gaia mission
• The Transiting Exoplanet Survey Satellite
• Gaia Early Data Release 3: The astrometric solution
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• Unresolved stellar companions with Gaia DR2 astrometry
• Astrometric exoplanet detection with Gaia
• The Hipparcos-Gaia Catalog of Accelerations: Gaia EDR3 Edition
• Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3
• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems
• orvara: An Efficient Code to Fit Orbits using Radial Velocity, Absolute, and/or Relative Astrometry
• Large eccentricity, low mutual inclination: the three-dimensional architecture of a hierarchical system of giant planets
• The CORALIE survey for southern extra-solar planets XV. Discovery of two eccentric planets orbiting HD4113 and HD156846
• Evidence for a high mutual inclination between the cold Jupiter and transiting super Earth orbiting $\pi$ Men
• The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets
• Detection of the nearest Jupiter analog in radial velocity and astrometry data
• Five Planets Transiting a Ninth Magnitude Star
• A Model-Independent Mass and Moderate Eccentricity for $\beta$ Pic b
• The instability of planetary systems in binaries: how the Kozai mechanism leads to strong planet-planet interactions
• The multiplicity of planet host stars - New low-mass companions to planet host stars
• Constraints on the mass and atmospheric composition and evolution of the low-density young planet DS Tuc A b
• The CORALIE survey for southern extrasolar planets XVIII. Three new massive planets and two low mass brown dwarfs at separation larger than 5 AU
• A significant mutual inclination between the planets within the $\pi$ Mensae system
• Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of Gaia
• The Magellan PFS Planet Search Program: Radial Velocity and Stellar Abundance Analyses of the 360 AU, Metal-Poor Binary "Twins" HD 133131A & B
• True masses of the long-period companions to HD 92987 and HD 221420 from Hipparcos-Gaia astrometry
• Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques
• A Possible Alignment Between the Orbits of Planetary Systems and their Visual Binary Companions
• The HARPS search for southern extra-solar planets XXXVI: Five new long-period giant planets and a system update
• Peculiar architectures for the WASP-53 and WASP-81 planet-hosting systems
• The Young Planet DS Tuc Ab has a Low Obliquity
• In the Presence of a Wrecking Ball: Orbital Stability in the HR 5183 System
• Biases in orbit fitting of directly-imaged exoplanets with small orbital coverage
• Galactic perturbations on the population of wide binary stars with exoplanets
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit
• Mutual inclinations between giant planets and their debris discs in HD 113337 and HD 38529
• The SOPHIE search for northern extrasolar planets. XVIII: Six new cold Jupiters, including one of the most eccentric exoplanet orbits
• HD 76920b pinned down: a detailed analysis of the most eccentric planetary system around an evolved star
• Boyajian's Star B: The co-moving stellar companion to KIC 8462852
• The California Legacy Survey I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades

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