Tides Between the TRAPPIST-1 Planets

Hamish C.F.C. Hay, Isamu Matsuyama

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The TRAPPIST-1 system is sufficiently closely packed that tides raised by one planet on another are significant. We investigate whether this source of tidal heating is comparable to eccentricity tides raised by the star. Assuming a homogeneous body with a Maxwell rheology, we find that energy dissipation from stellar tides always dominates over that from planet-planet tides across a range of viscosities. TRAPPIST-1 g may experience the greatest proportion of planet-planet tidal heating, where it can account for between 2% and 20% of the total amount of tidal heating, for high-viscosity (1021 Pa s) and low-viscosity (1014 Pa s) regimes, respectively. If planet-planet tidal heating is to exceed that from stellar eccentricity tides, orbital eccentricities must be no more than e = 10-3-10-4 for most of the TRAPPIST-1 planets.

Original languageEnglish (US)
Article number22
JournalAstrophysical Journal
Issue number1
StatePublished - Apr 10 2019


  • Gravitation
  • planets and satellites: Dynamical evolution and stability
  • planets and satellites: Individual (TRAPPIST-1g)
  • planets and satellites: Interiors
  • planets and satellites: Terrestrial planets

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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