Volume 616, August 2018
|Number of page(s)||14|
|Section||Planets and planetary systems|
|Published online||29 August 2018|
The GTC exoplanet transit spectroscopy survey
IX. Detection of haze, Na, K, and Li in the super-Neptune WASP-127b★
Instituto de Astrofísica de Canarias,
Vía Láctea s/n,
2 Departamento de Astrofísica, Universidad de La Laguna, Spain
3 Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, PR China
4 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
5 Dipartimento di Fisica, Universitá di Torino, Via P. Giuria 1, 10125 Torino, Italy
Accepted: 18 May 2018
Exoplanets with relatively clear atmospheres are prime targets for detailed studies of chemical compositions and abundances in their atmospheres. Alkali metals have long been suggested to exhibit broad wings due to pressure broadening, but most of the alkali detections only show very narrow absorption cores, probably because of the presence of clouds. We report the strong detection of the pressure-broadened spectral profiles of Na, K, and Li absorption in the atmosphere of the super-Neptune WASP-127b, at 4.1σ, 5.0σ, and 3.4σ, respectively. We performed a spectral retrieval modeling on the high-quality optical transmission spectrum newly acquired with the 10.4 m Gran Telescopio Canarias (GTC), in combination with the re-analyzed optical transmission spectrum obtained with the 2.5 m Nordic Optical Telescope (NOT). By assuming a patchy cloudy model, we retrieved the abundances of Na, K, and Li, which are super-solar at 3.7σ for K and 5.1σ for Li (and only 1.8σ for Na). We constrained the presence of haze coverage to be around 52%. We also found a hint of water absorption, but cannot constrain it with the global retrieval owing to larger uncertainties in the probed wavelengths. WASP-127b will be extremely valuable for atmospheric characterization in the era of James Webb Space Telescope.
Key words: planetary systems / planets and satellites: individual: WASP-127b / planets and satellites: atmospheres / techniques: spectroscopic
The reduced spectra and the narrow-band light-curves are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/616/A145
© ESO 2018
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