Breaking the chains: Hot super-Earth systems from migration and disruption of compact resonant chains

Research output: Contribution to journalArticle

Abstract

'Hot super-Earths' (or 'mini-Neptunes') between one and four times Earth's size with period shorter than 100 d orbit 30-50 per cent of Sun-like stars. Their orbital configuration - measured as the period ratio distribution of adjacent planets in multiplanet systems - is a strong constraint for formation models. Here, we use N-body simulations with synthetic forces from an underlying evolving gaseous disc to model the formation and long-term dynamical evolution of super-Earth systems. While the gas disc is present, planetary embryos grow and migrate inward to form a resonant chain anchored at the inner edge of the disc. These resonant chains are far more compact than the observed super-Earth systems. Once the gas dissipates, resonant chains may become dynamically unstable. They undergo a phase of giant impacts that spreads the systems out. Disc turbulence has no measurable effect on the outcome. Our simulations match observations if a small fraction of resonant chains remain stable, while most super- Earths undergo a late dynamical instability. Our statistical analysis restricts the contribution of stable systems to less than 25 per cent. Our results also suggest that the large fraction of observed single-planet systems does not necessarily imply any dichotomy in the architecture of planetary systems. Finally, we use the low abundance of resonances in Kepler data to argue that, in reality, the survival of resonant chains happens likely only in ~5 per cent of the cases. This leads to a mystery: in our simulations only 50-60 per cent of resonant chains became unstable, whereas at least 75 per cent (and probably 90-95 per cent) must be unstable to match observations.

Details

Authors
  • Andre Izidoro
  • Masahiro Ogihara
  • Sean N. Raymond
  • Alessandro Morbidelli
  • Arnaud Pierens
  • Bertram Bitsch
  • Christophe Cossou
  • Franck Hersant
Organisations
External organisations
  • University of Bordeaux
  • São Paulo State University
  • National Astronomical Observatory of Japan
  • University of Côte d'Azur
  • Côte d'Azur Observatory
  • University of Paris-Sud
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Disc interactions, Methods: Numerical, Planet, Planets and satellites: Dynamical evolution and stability, Planets and satellites: Formation, Protoplanetary discs
Original languageEnglish
Article numberstx1232
Pages (from-to)1750-1770
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume470
Issue number2
Publication statusPublished - 2017 Sep 11
Publication categoryResearch
Peer-reviewedYes