[en] Temperate Earth-sized exoplanets around late-M dwarfs offer a rare opportunity to explore under which conditions planets can develop hospitable climate conditions. The small stellar radius amplifies the atmospheric transit signature, making even compact secondary atmospheres dominated by N2 or CO2 amenable to characterization with existing instrumentation. Yet, despite large planet search efforts, detection of low-temperature Earth-sized planets around late-M dwarfs has remained rare and the TRAPPIST-1 system, a resonance chain of rocky planets with seemingly identical compositions, has not yet shown any evidence of volatiles in the system. Here we report the discovery of a temperate Earth-sized planet orbiting the cool M6 dwarf LP 791-18. The newly discovered planet, LP 791-18d, has a radius of 1.03 ± 0.04 R⊕ and an equilibrium temperature of 300-400 K, with the permanent night side plausibly allowing for water condensation. LP 791-18d is part of a coplanar system and provides a so-far unique opportunity to investigate a temperate exo-Earth in a system with a sub-Neptune that retained its gas or volatile envelope. On the basis of observations of transit timing variations, we find a mass of 7.1 ± 0.7 M⊕ for the sub-Neptune LP 791-18c and a mass of 0.9<SUB>−0.4</SUB><SUP>+0.5 M⊕ for the exo-Earth LP 791-18d. The interaction with the sub-Neptune prevents the complete circularization of LP 791-18d's orbit, result in gravitational g in continued tidal heating of LP 791-18d's interior and probably strong volcanic activity at the surface.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Peterson, Merrin S.; University of Montreal, Department of Physics
Benneke, Björn; University of Montreal, Department of Physics
Collins, Karen; Harvard Smithsonian Center for Astrophysics
Piaulet, Caroline; University of Montreal, Department of Physics
Crossfield, Ian J. M.; University of Kansas, Department of Physics and Astronomy
Ali-Dib, Mohamad; University of Montreal, Department of Physics, New York University, Abu Dhabi
Christiansen, Jessie L.; Infrared Processing and Analysis Center
Gagné, Jonathan; Planetarium of Rio Tinto Alcan and Institute for Research on Exoplanets, University of Montréal, Montreal, Quebec, Canada
Faherty, Jackie; American Museum for National History, New York, NY, USA
Kite, Edwin; Department of the Geological Sciences, University of Chicago, Chicago, IL, USA
Dressing, Courtney; University of California, Berkeley, Department of Astronomy
Charbonneau, David; Harvard Smithsonian Center for Astrophysics
Murgas, Felipe; Astrophysical Institute of the Canaries
Cointepas, Marion; Institute de Planetologie et d'Astrophysique de Grenoble
Almenara, Jose Manuel; Institute de Planetologie et d'Astrophysique de Grenoble
Bonfils, Xavier; Institute de Planetologie et d'Astrophysique de Grenoble
Kane, Stephen; University of California, Irvine, Department of Earth System Science
Werner, Michael W.; Jet Propulsion Laboratory
Gorjian, Varoujan; Jet Propulsion Laboratory
Roy, Pierre-Alexis; University of Montreal, Department of Physics
Shporer, Avi; MIT, Center for Space Research/Kavli Institute
Pozuelos, Francisco J.; Institute of Astrophysics of Andalucía (IAA-CSIC), Glorieta de la Astronomía s, Granada, Spain, Astrobiology Research Unit, University of Liège, Liège, Belgium
Socia, Quentin Jay; University of Arizona, Department of Astronomy and Steward Observatory
Cloutier, Ryan; Harvard Smithsonian Center for Astrophysics, McMaster University, Department of Physics and Astronomy
Dietrich, Jeremy; University of Arizona, Department of Astronomy and Steward Observatory
Irwin, Jonathan; Harvard Smithsonian Center for Astrophysics
Weiss, Lauren; University of Hawaii, Manoa
Waalkes, William; University of Colorado, Boulder, Department of Astrophysical and Planetary Sciences
Berta-Thomson, Zach; University of Colorado, Boulder, Department of Astrophysical and Planetary Sciences
Evans, Thomas; MIT, Center for Space Research/Kavli Institute
Apai, Daniel; University of Arizona, Department of Astronomy and Steward Observatory, University of Arizona, Department of Planetary Sciences
Parviainen, Hannu; Astrophysical Institute of the Canaries
Pallé, Enric; Astrophysical Institute of the Canaries
Narita, Norio; Astrophysical Institute of the Canaries, -, -
Howard, Andrew W.; California Institute of Technology, Division of Physics, Mathematics and Astronomy
Dragomir, Diana; University of New Mexico, Department of Physics and Astronomy
Barkaoui, Khalid ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Exoplanets in Transit: Identification and Characterization
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO)
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Ducrot, Elsa ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Exoplanets in Transit: Identification and Characterization
Benkhaldoun, Zouhair; University Cadi Ayyad, Morocco
Fukui, Akihiko; Astrophysical Institute of the Canaries, -
Mori, Mayuko; Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo, Bunkyoku, Tokyo, Japan
Nishiumi, Taku; Astrobiology Center, Osawa, Mitaka, Tokyo, Japan, Department of Astronomical Science, The Graduated University for Advanced Studies, Sokendai, Osawa, Mitaka, Tokyo, Japan, Department of Multi-Disciplinary Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo, Japan
Kawauchi, Kiyoe; Astrophysical Institute of the Canaries, -
Ricker, George; MIT, Center for Space Research/Kavli Institute
Latham, David W.; Harvard Smithsonian Center for Astrophysics
Winn, Joshua N.; Princeton University, Department of Astrophysical Sciences
Seager, Sara; MIT, Center for Space Research/Kavli Institute, MIT, Department of Earth and Planetary Science, MIT, Department of Earth and Planetary Science
Isaacson, Howard; University of California, Berkeley, Department of Astronomy
Bixel, Alex; University of Arizona, Department of Astronomy and Steward Observatory
Gibbs, Aidan; University of California, Los Angeles, Department of Physics and Astronomy
Jenkins, Jon M.; NASA Ames Research Center
Smith, Jeffrey C.; SETI Institute, California
Chavez, Jose Perez; Texas State University, Department of Physics, San Marcos, TX, USA
Rackham, Benjamin V.; MIT, Center for Space Research/Kavli Institute
Henning, Thomas; Max-Planck-Institute for Astronomy, Heidelberg
Gabor, Paul; Vatican Observatory
Chen, Wen-Ping; National Central University, Taiwan, Institute of Astronomy
Espinoza, Nestor; Space Telescope Science Institute, Baltimore, Maryland
Jensen, Eric L. N.; Swarthmore College, Department of Physics and Astronomy
Collins, Kevin I.; George Mason University, Virginia
Schwarz, Richard P.; Harvard Smithsonian Center for Astrophysics
Conti, Dennis M.; American Association of Variable Star Observers, Massachusetts
Wang, Gavin; Tsinghua International School, Beijing, China
Kielkopf, John F.; University of Louisville
Mao, Shude; CAS, National Astronomical Observatories
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