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. Howell; Laetitia Delrez; Julien de Wit; Daniel Foreman-Mackey; Daniel L. Holdsworth; Jérémy Leconte; Susan Lederer; Martin Turbet; Yaseen Almleaky; Zouhair Benkhaldoun; Pierre Magain; Brett Morris; Kevin Heng; Didier Queloz

doi:10.1038/s41550-017-0129

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arXiv · 1703.04166

A seven-planet resonant chain in TRAPPIST-1

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Abstract

The TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit this host star. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.77 d orbital period for the outermost planet, TRAPPIST-1h, which was unconstrained until now. This value matches our theoretical expectations based on Laplace relations and places TRAPPIST-1h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1h has a radius of 0.727 Earth radii and an equilibrium temperature of 173 K. We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with a low-activity, middle-aged, late M dwarf.

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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. Howell, Laetitia Delrez, Julien de Wit, Daniel Foreman-Mackey, Daniel L. Holdsworth, Jérémy Leconte, Susan Lederer, Martin Turbet, Yaseen Almleaky, Zouhair Benkhaldoun, Pierre Magain, Brett Morris, Kevin Heng, Didier Queloz. 2017-03-12. A seven-planet resonant chain in TRAPPIST-1. https://doi.org/10.1038/s41550-017-0129

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