A near-infrared transmission spectrum for the warm saturn HAT-P-12b

Michael R. Line, Heather Knutson, Drake Deming, Ashlee Wilkins, Jean Michel Desert

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


We present a Hubble Space Telescope Wide Field Camera-3 (WFC3) transmission spectrum for the transiting exoplanet HAT-P-12b. This warm (1000 K) sub-Saturn-mass planet has a smaller mass and a lower temperature than the hot Jupiters that have been studied so far. We find that the planet's measured transmission spectrum lacks the expected water absorption feature for a hydrogen-dominated atmosphere and is instead best described by a model with high-altitude clouds. Using a frequentist hypothesis testing procedure, we can rule out a hydrogen-dominated cloud-free atmosphere to 4.9σ. When combined with other recent WFC3 studies, our observations suggest that clouds may be common in exoplanetary atmospheres.

Original languageEnglish (US)
Article number183
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 1 2013
Externally publishedYes


  • planets and satellites: atmospheres
  • planets and satellites: individual (HAT-P-12b)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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