title: Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1.
abstract: One aim of modern astronomy is to detect temperate, Earth-like exoplanets that are well suited for atmospheric characterization. Recently, three Earth-sized planets were detected that transit (that is, pass in front of) a star with a mass just eight per cent that of the Sun, located 12 parsecs away. The transiting configuration of these planets, combined with the Jupiter-like size of their host star-named TRAPPIST-1-makes possible in-depth studies of their atmospheric properties with present-day and future astronomical facilities. Here we report the results of a photometric monitoring campaign of that star from the ground and space. Our observations reveal that at least seven planets with sizes and masses similar to those of 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, 9.1 and 12.35 days) are near-ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inwards. Moreover, the seven planets have equilibrium temperatures low enough to make possible the presence of liquid water on their surfaces.
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
authors.forename: Michaël
authors.initials: M
authors.lastname: Gillon
authors.affiliation: Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK.
authors.forename: Amaury H M J
authors.initials: AH
authors.lastname: Triaud
authors.affiliation: University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern, Switzerland.|Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Brice-Olivier
authors.initials: BO
authors.lastname: Demory
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
authors.forename: Emmanuël
authors.initials: E
authors.lastname: Jehin
authors.affiliation: Astronomy Department, University of Washington, Seattle, Washington 98195, USA.|NASA Astrobiology Institute's Virtual Planetary Laboratory, Seattle, Washington 98195, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Agol
authors.affiliation: Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Deck
authors.affiliation: NASA Johnson Space Center, 2101 NASA Parkway, Houston, Texas 77058, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Lederer
authors.affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: Julien
authors.initials: J
authors.lastname: de Wit
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
authors.forename: Artem
authors.initials: A
authors.lastname: Burdanov
authors.affiliation: Spitzer Science Center, California Institute of Technology, 1200 E California Boulevard, Mail Code 314-6, Pasadena, California 91125, USA.
authors.forename: James G
authors.initials: JG
authors.lastname: Ingalls
authors.affiliation: NaXys, Department of Mathematics, University of Namur, 8 Rempart de la Vierge, 5000 Namur, Belgium.|Laboratoire AIM Paris-Saclay, CEA/DRF-CNRS-Univ. Paris Diderot - IRFU/SAp, Centre de Saclay, F- 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Emeline
authors.initials: E
authors.lastname: Bolmont
authors.affiliation: Laboratoire d'astrophysique de Bordeaux, Université Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, F-33615 Pessac, France.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Leconte
authors.affiliation: Laboratoire d'astrophysique de Bordeaux, Université Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, F-33615 Pessac, France.
authors.forename: Sean N
authors.initials: SN
authors.lastname: Raymond
authors.affiliation: Laboratoire d'astrophysique de Bordeaux, Université Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, F-33615 Pessac, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Selsis
authors.affiliation: Laboratoire de Météorologie Dynamique, Sorbonne Universités, UPMC Univ Paris 06, CNRS, 4 Place Jussieu, 75005 Paris, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Turbet
authors.affiliation: Laboratoire LPHEA, Oukaimeden Observatory, Cadi Ayyad University/FSSM, BP 2390 Marrakesh, Morocco.
authors.forename: Khalid
authors.initials: K
authors.lastname: Barkaoui
authors.affiliation: Center for Astrophysics and Space Science, University of California San Diego, La Jolla, California 92093, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Burgasser
authors.affiliation: Leicester Institute for Space and Earth Observation, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Burleigh
authors.affiliation: Spitzer Science Center, California Institute of Technology, 1200 E California Boulevard, Mail Code 314-6, Pasadena, California 91125, USA.
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Carey
authors.affiliation: Leicester Institute for Space and Earth Observation, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: Aleksander
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authors.lastname: Chaushev
authors.affiliation: Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5RF, UK.
authors.forename: Chris M
authors.initials: CM
authors.lastname: Copperwheat
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.|Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Delrez
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
authors.forename: Catarina S
authors.initials: CS
authors.lastname: Fernandes
authors.affiliation: Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Holdsworth
authors.affiliation: South African Astronomical Observatory, PO Box 9, Observatory, 7935, South Africa.
authors.forename: Enrico J
authors.initials: EJ
authors.lastname: Kotze
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
authors.forename: Valérie
authors.initials: V
authors.lastname: Van Grootel
authors.affiliation: Space and Astronomy Department, Faculty of Science, King Abdulaziz University, 21589 Jeddah, Saudi Arabia.|King Abdullah Centre for Crescent Observations and Astronomy, Makkah Clock, Mecca 24231, Saudi Arabia.
authors.forename: Yaseen
authors.initials: Y
authors.lastname: Almleaky
authors.affiliation: Laboratoire LPHEA, Oukaimeden Observatory, Cadi Ayyad University/FSSM, BP 2390 Marrakesh, Morocco.
authors.forename: Zouhair
authors.initials: Z
authors.lastname: Benkhaldoun
authors.affiliation: Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bat. B5C, 4000 Liège, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Magain
authors.affiliation: Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK.|Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny, Switzerland.
authors.forename: Didier
authors.initials: D
authors.lastname: Queloz
mesh_terms: D018559:Exobiology; D005118:Extraterrestrial Environment / Q000737:chemistry; D016083:Planets; D055609:Stars, Celestial; D013696:Temperature; D014867:Water / Q000032:analysis / Q000737:chemistry
chemical_list: D014867:Water