Ground- A nd Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab

Danielle Piskorz, Cam Buzard, Michael Line, Heather A. Knutson, Björn Benneke, Nathan R. Crockett, Alexandra C. Lockwood, Geoffrey A. Blake, Travis S. Barman, Chad F. Bender, Drake Deming, John A. Johnson

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


We describe the detection of water vapor in the atmosphere of the transiting hot Jupiter KELT-2Ab by treating the star-planet system as a spectroscopic binary with high-resolution, ground-based spectroscopy. We resolve the signal of the planet's motion with deep combined flux observations of the star and the planet. In total, six epochs of Keck NIRSPEC L-band observations were obtained, and the full data set was subjected to a cross-correlation analysis with a grid of self-consistent atmospheric models. We measure a radial projection of the Keplerian velocity, K P, of 148 ± 7 km s-1, consistent with transit measurements, and detect water vapor at 3.8σ. We combine NIRSPEC L-band data with Spitzer IRAC secondary eclipse data to further probe the metallicity and carbon-to-oxygen ratio of KELT-2Ab's atmosphere. While the NIRSPEC analysis provides few extra constraints on the Spitzer data, it does provide roughly the same constraints on metallicity and carbon-to-oxygen ratio. This bodes well for future investigations of the atmospheres of non-transiting hot Jupiters.

Original languageEnglish (US)
Article number133
JournalAstronomical Journal
Issue number3
StatePublished - Sep 2018

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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