QUADRUPOLE AND EMISSION FROM URANUS: THE URANIAN THERMOSPHERE, H 2 H 3 IONOSPHERE, AND AURORA

We present an analysis of the near-infrared emission of Uranus, obtained from 1993 to 1995 at the United Kingdom Infrared Telescope (UKIRT) and the NASA Infrared Telescope Facility (IRTF). We report that in contrast to Jupiter and Saturn, prominent emission in the quadrupole and over- H 2 H 3 tone and fundamental bands occurs globally. The rotational temperature and luminosity of and H 2 H 3 were usually found to vary mildly with longitude. The and possibly the temperature appears to H 2 ,H 3, vary with apparition, indicating a long-term variability of Uranuss thermospheric structure. The ther- mosphere cooled between 1992 and 1995, while the ionosphere either cooled or otherwise suUered a decline in the column of excited The luminosity in