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Alexander Mustill. Profile picture.

Alexander Mustill

Researcher

Alexander Mustill. Profile picture.

Dynamical orbital evolution scenarios of the wide-orbit eccentric planet HR 5183b

Author

  • Alexander J. Mustill
  • Melvyn B. Davies
  • Sarah Blunt
  • Andrew Howard

Summary, in English

The recently discovered giant exoplanet HR5183b exists on a wide, highly eccentric orbit (a = 18 au, e = 0.84). Its host star possesses a common proper-motion companion which is likely on a bound orbit. In this paper, we explore scenarios for the excitation of the eccentricity of the planet in binary systems such as this, considering planet-planet scattering, Lidov-Kozai cycles from the binary acting on a single-planet system, or Lidov-Kozai cycles acting on a two-planet system that also undergoes scattering. Planet-planet scattering, in the absence of a binary companion, has a $2.8{-}7.2{{ rm per cent}}$ probability of pumping eccentricities to the observed values in our simulations, depending on the relative masses of the two planets. Lidov-Kozai cycles from the binary acting on an initially circular orbit can excite eccentricities to the observed value but require very specific orbital configurations for the binary and overall there is a low probability of catching the orbit at the high observed high eccentricity ($0.6{{ rm per cent}}$). The best case is provided by planet-planet scattering in the presence of a binary companion: here, the scattering provides the surviving planet with an initial eccentricity boost that is subsequently further increased by Kozai cycles from the binary. We find a success rate of $14.5{{ rm per cent}}$ for currently observing e ≥ 0.84 in this set-up. The single-planet plus binary and two-planet plus binary cases are potentially distinguishable if the mutual inclination of the binary and the planet can be measured, as the latter permits a broader range of mutual inclinations. The combination of scattering and Lidov-Kozai forcing may also be at work in other wide-orbit eccentric giant planets, which have a high rate of stellar binary companions.

Department/s

  • Lund Observatory
  • Lund University Bioimaging Center

Publishing year

2022-01-01

Language

English

Pages

3616-3625

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

509

Issue

3

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • binaries: general
  • planets and satellites: dynamical evolution and stability
  • planets and satellites: formation
  • stars: individual: HR5183

Status

Published

Project

  • IMPACT: Comets, asteroids and the habitability of planets
  • Consolidating CHEOPS and preparing for PLATO: Exoplanet studies in the 2020s

ISBN/ISSN/Other

  • ISSN: 0035-8711