Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1

Research output: Contribution to journalArticlepeer-review


  • Michael Gillon
  • Brice-Olivier Demory
  • Emmanuel Jehin
  • Eric Agol
  • Katherine M. Deck
  • Susan M. Lederer
  • Julien de Wit
  • Artem Burdanov
  • James G. Ingalls
  • Emeline Bolmont
  • Jeremy Leconte
  • Sean N. Raymond
  • Franck Selsis
  • Martin Turbet
  • Khalid Barkaoui
  • Adam Burgasser
  • Matthew R. Burleigh
  • Sean J. Carey
  • Aleksander Chaushev
  • Chris M. Copperwheat
  • Laetitia Delrez
  • Catarina S. Fernandes
  • Daniel L. Holdsworth
  • Enrico J. Kotze
  • Valerie Van Grootel
  • Yaseen Almleaky
  • Zouhair Benkhaldoun
  • Pierre Magain
  • Didier Queloz

Colleges, School and Institutes


One focus of modern astronomy is to detect temperate terrestrial exoplanets well-suited for atmospheric characterisation. A milestone was recently achieved with the detection of three Earth-sized planets transiting (i.e. passing in front of) a star just 8% the mass of the Sun 12 parsecs away. Indeed, the transiting configuration of these planets with the Jupiter-like size of their host star - named TRAPPIST-1 - makes possible in-depth studies of their atmospheric properties with current and future astronomical facilities. Here we report the results of an intensive photometric monitoring campaign of that star from the ground and with the Spitzer Space Telescope. Our observations reveal that at least seven planets with sizes and masses similar to the Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.21, 12.35 days) are near ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inward. The seven planets have equilibrium temperatures low enough to make possible liquid water on their surfaces.

Bibliographic note

27 pages


Original languageEnglish
Pages (from-to)456-460
Issue number7642
Early online date22 Feb 2017
Publication statusPublished - 4 Mar 2017


  • astro-ph.EP