Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS): V. Detection of sodium on the bloated super-Neptune WASP-166b

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Planet formation processes or evolution mechanisms are surmised to be at the origin of the hot Neptune desert. Studying exoplanets currently living within or at the edge of this desert could allow disentangling the respective roles of formation and evolution. We present the High Accuracy Radial velocity Planet Searcher (HARPS) transmission spectrum of the bloated super-Neptune WASP-166b, located at the outer rim of the Neptune desert. Neutral sodium is detected at the 3.4σ level (0.455†±â€ 0.135%), with a tentative indication of line broadening, which could be caused by winds blowing sodium farther into space, a possible manifestation of the bloated character of these highly irradiated worlds. We put this detection into context with previous work claiming a non-detection of sodium in the same observations and show that the high noise in the trace of the discarded stellar sodium lines was responsible for the non-detection. We highlight the impact of this low signal-to-noise ratio remnant on detections for exoplanets similar to WASP-166b.


  • J. V. Seidel
  • D. Ehrenreich
  • V. Bourrier
  • R. Allart
  • O. Attia
  • H. J. Hoeijmakers
  • M. Lendl
  • E. Linder
  • A. Wyttenbach
  • N. Astudillo-Defru
  • D. Bayliss
  • H. M. Cegla
  • K. Heng
  • B. Lavie
  • C. Lovis
  • C. Melo
  • F. Pepe
  • L. A. Dos Santos
  • D. Ségransan
  • S. Udry
Enheter & grupper
Externa organisationer
  • University of Geneva
  • University of Bern
  • Space Research Institute, AAS
  • University Grenoble Alpes
  • Universidad Católica de la Santísima Concepción
  • University of Warwick
  • European Southern Observatory Santiago

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Astronomi, astrofysik och kosmologi


TidskriftAstronomy and Astrophysics
StatusPublished - 2020
Peer review utfördJa