Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets?

R. F. Maldonado, E. Villaver, A. J. Mustill, M. Chávez, E. Bertone

Research output: Contribution to journalArticlepeer-review


We investigate the origin of close-in planets and related phenomena orbiting white dwarfs (WDs), which are thought to originate from orbits more distant from the star. We use the planetary architectures of the 75 multiple-planet systems (four, five, and six planets) detected orbiting main-sequence stars to build 750 dynamically analogous templates that we evolve to the WD phase. Our exploration of parameter space, although not exhaustive, is guided and restricted by observations and we find that the higher the multiplicity of the planetary system, the more likely it is to have a dynamical instability (losing planets, orbit crossing, and scattering), that eventually will send a planet (or small object) through a close periastron passage. Indeed, the fraction of unstable four- to six-planet simulations is comparable to the 25-50 per cent fraction of WDs having atmospheric pollution. Additionally, the onset of instability in the four- to six-planet configurations peaks in the first Gyr of the WD cooling time, decreasing thereafter. Planetary multiplicity is a natural condition to explain the presence of close-in planets to WDs, without having to invoke the specific architectures of the system or their migration through the von Zeipel-Lidov-Kozai effects from binary companions or their survival through the common envelope phase.

Original languageEnglish
Pages (from-to)L43-L48
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
Publication statusPublished - 2021

Subject classification (UKÄ)

  • Astronomy, Astrophysics and Cosmology


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


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