Detection of H3(+) from Uranus

The detection of H3(+) in Uranus is reported. Using the CGS4 spectrometer on the UKIRT telescope, we clearly detected 11 emission features of the H3(+) fundamental vibration-rotation band between 3.89 and 4.09 microns. These features are composed primarily of lines from the Q-branch; the strongest of them is the Q(3) blend at 3.985 microns. Analysis of these features indicates a rotational temperature of 740 +/- 25 K, an ortho-H3(+) fraction of 0.51 +/- 0.03, and a disk-averaged H3(+) column abundance of 6.5 x 10 exp 10 (+/- 10 percent) molecules/sq cm. Comparison is made with Jupiter, Saturn, and Neptune. A detection of the H2 1-0 S(1) line in Uranus and an upper limit to H3(+) 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.