NEAR-IR DIRECT DETECTION OF WATER VAPOR IN TAU BOÖTIS b

We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity (RV) variations of the hot Jupiter in the [tau] Bootis 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 [tau] 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 6[sigma] detection of the planet at K sub(p) = 111 + or - 5 km s super(-1), with a l[sigma] upper limit on the spectroscopic flux ratio of 10 super(-4). This RV leads to a planetary orbital inclination of i = (ProQuest: Formulae and/or non-USASCII text omitted) and a mass of M sub(P) = (ProQuest: Formulae and/or non-USASCII text omitted) M sub(Jup). We report the first detection of water vapor in the atmosphere of a non-transiting hot Jupiter, [tau] Boo b.