[en] WASP-107b is a warm (approximately 740 K) transiting planet with a Neptune-like mass of roughly 30.5 M<SUB>⊕</SUB> and Jupiter-like radius of about 0.94 R<SUB>J</SUB> (refs. <SUP>1,2</SUP>), whose extended atmosphere is eroding<SUP>3</SUP>. Previous observations showed evidence for water vapour and a thick, high-altitude condensate layer in the atmosphere of WASP-107b (refs. <SUP>4,5</SUP>). Recently, photochemically produced sulfur dioxide (SO<SUB>2</SUB>) was detected in the atmosphere of a hot (about 1,200 K) Saturn-mass planet from transmission spectroscopy near 4.05 μm (refs. <SUP>6,7</SUP>), but for temperatures below about 1,000 K, sulfur is predicted to preferably form sulfur allotropes instead of SO<SUB>2</SUB> (refs. <SUP>8-10</SUP>). Here we report the 9σ detection of two fundamental vibration bands of SO<SUB>2</SUB>, at 7.35 μm and 8.69 μm, in the transmission spectrum of WASP-107b using the Mid-Infrared Instrument (MIRI) of JWST. This discovery establishes WASP-107b as the second irradiated exoplanet with confirmed photochemistry, extending the temperature range of exoplanets exhibiting detected photochemistry from about 1,200 K down to about 740 K. Furthermore, our spectral analysis reveals the presence of silicate clouds, which are strongly favoured (around 7σ) over simpler cloud set-ups. Furthermore, water is detected (around 12σ) but methane is not. These findings provide evidence of disequilibrium chemistry and indicate a dynamically active atmosphere with a super-solar metallicity.
Research Center/Unit :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Dyrek, Achrène ✱; Université Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM, Gif-sur-Yvette, France
Min, Michiel ✱; Netherlands Institute for Space Research
Decin, Leen ✱; Katholieke University of Leuven, Astronomical Institute
Bouwman, Jeroen; Max-Planck-Institute for Astronomy, Heidelberg
Crouzet, Nicolas; Leiden Observatory
Mollière, Paul; Max-Planck-Institute for Astronomy, Heidelberg
Lagage, Pierre-Olivier; CEA Saclay, Service d'Astrophysique
Konings, Thomas; Katholieke University of Leuven, Astronomical Institute
Tremblin, Pascal; Université Paris-Saclay, UVSQ, CNRS, CEA, Maison de la Simulation, Gif-sur-Yvette, France
Güdel, Manuel; Max-Planck-Institute for Astronomy, Heidelberg, University of Vienna, Department of Astronomy, ETH Zurich, Department of Physics
Pye, John; Space Research Centre, School of Physics &, Astronomy, University of Leicester, Leicester, UK
Waters, Rens; Netherlands Institute for Space Research, Radboud University Nijmegen, Department of Astronomy and Physics, -
Henning, Thomas; Max-Planck-Institute for Astronomy, Heidelberg
Vandenbussche, Bart; Katholieke University of Leuven, Astronomical Institute
Ardevol Martinez, Francisco; Netherlands Institute for Space Research, University of Groningen, Kapteyn Astronomical Institute, University of Edinburgh, Centre for Astrobiology, University of Edinburgh, School of Geosciences
Argyriou, Ioannis; Katholieke University of Leuven, Astronomical Institute
Ducrot, Elsa; CEA Saclay, Service d'Astrophysique
Heinke, Linus; Katholieke University of Leuven, Astronomical Institute, University of Edinburgh, Centre for Astrobiology, University of Edinburgh, School of Geosciences
van Looveren, Gwenael; University of Vienna, Department of Astronomy
Absil, Olivier ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO)
Barrado, David; Center for Astrobiology, Madrid
Baudoz, Pierre; LESIA, Observatoire de Paris, CNRS, Université Paris Cité, Sorbonne Université, Meudon, France
Boccaletti, Anthony; LESIA, Observatoire de Paris, CNRS, Université Paris Cité, Sorbonne Université, Meudon, France
Cossou, Christophe; Département d'Electronique des Détecteurs et d'Informatique pour la Physique, Université Paris-Saclay, CEA, Gif-sur-Yvette, France
Coulais, Alain; CEA Saclay, Service d'Astrophysique, Laboratoire d'Etudes du Rayonnement de la Matiere en Astrophysique
Edwards, Billy; Netherlands Institute for Space Research
Gastaud, René; Département d'Electronique des Détecteurs et d'Informatique pour la Physique, Université Paris-Saclay, CEA, Gif-sur-Yvette, France
Glasse, Alistair; Royal Observatory Edinburgh
Glauser, Adrian; ETH Zurich, Department of Physics
Greene, Thomas P.; Space Science and Astrobiology Division, NASA's Ames Research Center, Moffett Field, CA, USA
Kendrew, Sarah; Space Telescope Science Institute, ESA Office, Baltimore, Maryland
Krause, Oliver; Max-Planck-Institute for Astronomy, Heidelberg
Lahuis, Fred; Netherlands Institute for Space Research
Mueller, Michael; University of Groningen, Kapteyn Astronomical Institute
Olofsson, Goran; AlbaNova University Center
Patapis, Polychronis; ETH Zurich, Department of Physics
Rouan, Daniel; Center for Astrobiology, Madrid
Royer, Pierre; Katholieke University of Leuven, Astronomical Institute
Scheithauer, Silvia; Max-Planck-Institute for Astronomy, Heidelberg
Waldmann, Ingo; University College London, Department of Physics and Astronomy
Whiteford, Niall; American Museum of Natural History, New York
Colina, Luis; Center for Astrobiology, Madrid
van Dishoeck, Ewine F.; Leiden Observatory
Östlin, Göran; Université Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM, Gif-sur-Yvette, France, Department of Astronomy, Oskar Klein Centre, Stockholm University, Stockholm, Sweden
Ray, Tom P.; Dublin Institute for Advanced Studies, School of Cosmic Physics
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