A seven-planet resonant chain in TRAPPIST-1

Rodrigo Luger*, Marko Sestovic, Ethan Kruse, Simon L. Grimm, Brice Olivier Demory, Eric Agol, Emeline Bolmont, Daniel Fabrycky, Catarina S. Fernandes, Valérie Van Grootel, Adam Burgasser, Michaël Gillon, James G. Ingalls, Emmanuël Jehin, Sean N. Raymond, Franck Selsis, Amaury H.M.J. Triaud, Thomas Barclay, Geert Barentsen, Steve B. HowellLaetitia Delrez, Julien De Wit, Daniel Foreman-Mackey, Daniel L. Holdsworth, Jérémy Leconte, Susan Lederer, Martin Turbet, Yaseen Almleaky, Zouhair Benkhaldoun, Pierre Magain, Brett M. Morris, Kevin Heng, DIdier Queloz, Amaury Triaud

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

160 Citations (Scopus)


The TRAPPIST-1 system is the first transiting planet system found orbiting an ultracool dwarf star 1. At least seven planets similar in radius to Earth were previously found to transit this host star 2. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.77 day orbital period for the outermost transiting planet, TRAPPIST-1 h, which was previously unconstrained. This value matches our theoretical expectations based on Laplace relations 3 and places TRAPPIST-1 h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1 h has a radius of 0.752 R ⊠• and an equilibrium temperature of 173 K. We have also measured the rotational period of the star to be 3.3 days and detected a number of flares consistent with a low-activity, middle-aged, late M dwarf.

Original languageEnglish
Article number0129
JournalNature Astronomy
Publication statusPublished - 22 May 2017

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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