Spake, JJ;
Sing, DK;
Wakeford, HR;
Nikolov, N;
Mikal-Evans, T;
Deming, D;
Barstow, JK;
... Wheatley, PJ; + view all
(2020)
Abundance measurements of H₂O and carbon-bearing species in the atmosphere of WASP-127b confirm its super-solar metallicity.
Monthly Notices of the Royal Astronomical Society
10.1093/mnras/staa3116.
(In press).
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Abstract
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 RJ), sub-Saturn mass (0.19 MJ) 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, H2O, and CO2, 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 super-solar, 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 super-solar CO2 volume mixing ratios, which adds to the likelihood that WASP-127b’s bulk metallicity is super-solar, since CO2 abundance is highly sensitive to atmospheric metallicity. We detect water at a significance of 13.7 σ. 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 JWST will be able to constrain WASP-127b’s C/O ratio, and may reveal the formation history of this metal-enriched, highly observable exoplanet.
| Type: | Article |
|---|---|
| Title: | Abundance measurements of H₂O and carbon-bearing species in the atmosphere of WASP-127b confirm its super-solar metallicity |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/staa3116 |
| Publisher version: | https://doi.org/10.1093/mnras/staa3116 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | techniques: spectroscopic, planets and satellites: atmospheres, stars: individual: WASP-127 |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10112827 |
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