DETECTION OF H-3(+) FROM URANUS

The detection of H-3+ in Uranus is reported. Using the CGS4 spectrometer on the UKIRT telescope, we clearly detected 11 emission features of the H-3+ fundamental vibration-rotation band between 3.89 and 4.09 mum. These features are composed primarily of lines from the Q-branch; the strongest of them is the Q(3) blend at 3.985 mum. Analysis of these features indicates a rotational temperature of 740 +/- 25 K, an ortho-H-3+ fraction of 0.51 +/- 0.03, and a disk-averaged H-3+ column abundance of 6.5 x 10(10) (+/- 10%) molecules cm-2. Comparison is made with Jupiter (the only other planet for which H-3+ has been detected), Saturn, and Neptune. A detection of the H-2 1-0 S(1) line in Uranus and an upper limit to H-3+ emission from Neptune also are reported. The rate of energy deposition into Uranus appears to be significantly higher than the rate reported during the Voyager 2 flyby in January of 1986.