NEAR-IR direct detection of water vapor in tau Boötis b

Alexandra C. Lockwood, John A. Johnson, Chad F. Bender, John S. Carr, Travis Barman, Alexander J.W. Richert, Geoffrey A. Blake

Research output: Contribution to journalArticlepeer-review

86 Scopus citations


We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity (RV) variations of the hot Jupiter in the τ Boötis planetary system. The detection of an exoplanet by the shift in the stellar spectrum alone provides a measure of the planet's minimum mass, with the true mass degenerate with the unknown orbital inclination. Treating the τ Boo system as a high flux ratio double-lined spectroscopic binary permits the direct measurement of the planet's true mass as well as its atmospheric properties. After removing telluric absorption and cross-correlating with a model planetary spectrum dominated by water opacity, we measure a 6σ detection of the planet at Kp = 111 ± 5 km s-1, with a 1σ upper limit on the spectroscopic flux ratio of 10-4. This RV leads to a planetary orbital inclination of i = 45+3-4° and a mass of Mp = 5.90+0.35-0.20 MJup. We report the first detection of water vapor in the atmosphere of a non-transiting hot Jupiter, τ Boo b.

Original languageEnglish (US)
Article numberL29
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Mar 10 2014


  • atmospheres - techniques
  • planets and satellites
  • spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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