Article (Scientific journals)
Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
De Wit, J.; Wakeford, H. R.; Lewis, N. K. et al.
2018In Nature Astronomy, 2 (3), p. 214-219
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Abstract :
[en] Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2 ). Their atmospheric regime is unknown and could range from extended primordial hydrogen-dominated to depleted atmospheres 3-6 . Hydrogen in particular is a powerful greenhouse gas that may prevent the habitability of inner planets while enabling the habitability of outer ones 6-8 . An atmosphere largely dominated by hydrogen, if cloud-free, should yield prominent spectroscopic signatures in the near-infrared detectable during transits. Observations of the innermost planets have ruled out such signatures 9 . However, the outermost planets are more likely to have sustained such a Neptune-like atmosphere 10, 11 . Here, we report observations for the four planets within or near the system's habitable zone, the circumstellar region where liquid water could exist on a planetary surface 12-14 . These planets do not exhibit prominent spectroscopic signatures at near-infrared wavelengths either, which rules out cloud-free hydrogen-dominated atmospheres for TRAPPIST-1 d, e and f, with significance of 8σ, 6σ and 4σ, respectively. Such an atmosphere is instead not excluded for planet g. As high-altitude clouds and hazes are not expected in hydrogen-dominated atmospheres around planets with such insolation 15, 16, these observations further support their terrestrial and potentially habitable nature. © 2018 The Author(s).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
De Wit, J.;  Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
Wakeford, H. R.;  Astrophysics Group, University of Exeter, Devon, United Kingdom, Space Telescope Science Institute, Baltimore, MD, United States
Lewis, N. K.;  Space Telescope Science Institute, Baltimore, MD, United States
Delrez, Laetitia ;  Astrophysics Group, Cavendish Laboratory, Cambridge, United Kingdom
Gillon, Michaël  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Selsis, F.;  Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France
Leconte, J.;  Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France
Demory, B.-O.;  University of Bern, Center for Space and Habitability, Bern, Switzerland
Bolmont, E.;  Astrophysics Division of CEA de Saclay, Gif-sur-Yvette, France
Bourrier, V.;  Observatoire de l'Université de Genève, Sauverny, Switzerland
Burgasser, A. J.;  Center for Astrophysics and Space Science, University of California, San Diego, San Diego, CA, United States
Grimm, S.;  University of Bern, Center for Space and Habitability, Bern, Switzerland
Jehin, Emmanuel  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Lederer, S. M.;  NASA Johnson Space Center, Houston, TX, United States
Owen, J. E.;  Astrophysics Group, Imperial College London, Blackett Laboratory, London, United Kingdom
Stamenković, V.;  Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
Triaud, A. H. M. J.;  School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom
More authors (7 more) Less
Language :
English
Title :
Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
Publication date :
2018
Journal title :
Nature Astronomy
eISSN :
2397-3366
Publisher :
Nature Publishing Group
Volume :
2
Issue :
3
Pages :
214-219
Peer reviewed :
Peer Reviewed verified by ORBi
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