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Alexander Mustill. Profile picture.

Alexander Mustill

Researcher

Alexander Mustill. Profile picture.

Unstable low-mass planetary systems as drivers of white dwarf pollution

Author

  • Alexander J. Mustill
  • Eva Villaver
  • Dimitri Veras
  • Boris T. Gänsicke
  • Amy Bonsor

Summary, in English

At least 25 percent of white dwarfs show atmospheric pollution by metals, sometimes accompanied by detectable circumstellar dust/gas discs or (in the case of WD 1145+017) transiting disintegrating asteroids. Delivery of planetesimals to the white dwarf by orbiting planets is a leading candidate to explain these phenomena. Here, we study systems of planets and planetesimals undergoing planet–planet scattering triggered by the star's post-main-sequence mass loss, and test whether this can maintain high rates of delivery over the several Gyr that they are observed. We find that low-mass planets (Earth to Neptune mass) are efficient deliverers of material and can maintain the delivery for Gyr. Unstable low-mass planetary systems reproduce the observed delayed onset of significant accretion, as well as the slow decay in accretion rates at late times. Higher-mass planets are less efficient, and the delivery only lasts a relatively brief time before the planetesimal populations are cleared. The orbital inclinations of bodies as they cross the white dwarf's Roche limit are roughly isotropic, implying that significant collisional interactions of asteroids, debris streams and discs can be expected. If planet–planet scattering is indeed responsible for the pollution of white dwarfs, many such objects, and their main-sequence progenitors, can be expected to host (currently undetectable) super-Earth planets on orbits of several au and beyond.

Department/s

  • Lund Observatory

Publishing year

2018-05-01

Language

English

Pages

3939-3955

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

476

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Kuiper Belt: general
  • planets and satellites: dynamical evolution and stability
  • stars: AGB and post-AGB
  • circumstellar matter
  • planetary systems
  • white dwarfs
  • Astrophysics - Earth and Planetary Astrophysics

Status

Published

Project

  • Polluting white dwarfs through planetary instability
  • IMPACT: Comets, asteroids and the habitability of planets

ISBN/ISSN/Other

  • ISSN: 1365-2966