Reference : Abundance measurements of H[SUB]2[/SUB]O and carbon-bearing species in the atmosphere...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
Abundance measurements of H[SUB]2[/SUB]O and carbon-bearing species in the atmosphere of WASP-127b confirm its supersolar metallicity
Spake, Jessica J. mailto [Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 3RF, UK]
Sing, David K. [Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 3RF, UK]
Wakeford, Hannah R. [School of Physics, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK]
Nikolov, Nikolay [Space Telescope Science Institute, 3700 San Martin Dr, Baltimore, MD 21218, USA]
Mikal-Evans, Thomas [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 37-241, Cambridge, MA 02139, USA]
Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742, USA]
Barstow, Joanna K. [School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK]
Anderson, David R. [Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK]
Carter, Aarynn L. [Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 3RF, UK]
Gillon, Michaël mailto [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic >]
Goyal, Jayesh M. [Department of Astronomy and Carl Sagan Institute, Cornell University, 122 Sciences Drive, Ithaca, NY 14853, USA]
Hebrard, Guillaume [Sorbonne Universite, CNRS, UMR 7095, Institut d'Astrophysique de Paris, 98 bis bd Arago, F-75014 Paris, France]
Hellier, Coel [Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK]
Kataria, Tiffany [NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA]
Lam, Kristine W. F. [Center for Astronomy and Astrophysics, Technical University Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany]
Triaud, A. H. M. J. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK]
Wheatley, Peter J. [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK)]
Monthly Notices of the Royal Astronomical Society
Oxford University Press
United Kingdom
[en] techniques: spectroscopic ; planets and satellites: atmospheres ; stars: individual: WASP-127 ; Astrophysics - Earth and Planetary Astrophysics
[en] The chemical abundances of exoplanet atmospheres may provide valuable information about the bulk compositions, formation pathways, and evolutionary histories of planets. Exoplanets with large, relatively cloud-free atmospheres, and which orbit bright stars provide the best opportunities for accurate abundance measurements. For this reason, we measured the transmission spectrum of the bright (V ∼ 10.2), large (1.37 R[SUB]J[/SUB]), sub-Saturn mass (0.19 M[SUB]J[/SUB]) exoplanet WASP-127b across the near-UV to near-infrared wavelength range (0.3-5 μm), using the Hubble and Spitzer Space Telescopes. Our results show a feature-rich transmission spectrum, with absorption from Na, H[SUB]2[/SUB]O, and CO[SUB]2[/SUB], and wavelength-dependent scattering from small-particle condensates. We ran two types of atmospheric retrieval models: one enforcing chemical equilibrium, and the other which fit the abundances freely. Our retrieved abundances at chemical equilibrium for Na, O, and C are all supersolar, with abundances relative to solar values of 9 $^{+15}_{-6}$ , 16 $^{+7}_{-5}$ , and 26 $^{+12}_{-9}$ , respectively. Despite giving conflicting C/O ratios, both retrievals gave supersolar CO[SUB]2[/SUB] volume mixing ratios, which adds to the likelihood that WASP-127b's bulk metallicity is supersolar, since CO[SUB]2[/SUB] abundance is highly sensitive to atmospheric metallicity. We detect water at a significance of 13.7σ. Our detection of Na is in agreement with previous ground-based detections, though we find a much lower abundance, and we also do not find evidence for Li or K despite increased sensitivity. In the future, spectroscopy with James Webb Space Telescope will be able to constrain WASP-127b's C/O ratio, and may reveal the formation history of this metal-enriched, highly observable exoplanet.

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