ATOMIC-HYDROGEN CORONA OF URANUS

We have analyzed Voyager 2 ultraviolet spectrometer observations of th e H Lyman alpha emission from the atomic hydrogen corona of Uranus. Th e resulting estimated hydrogen density distribution has a radial profi le proportional to 1/r(2). This distribution implies a weakly bound or escaping population of hot (greater than or similar to 2 eV) hydrogen not thermalized with the 0.07 eV thermosphere/exosphere. The hot H de nsity is enhanced on the sunward side of Uranus, with the maximum weak ly associated with the dayside magnetic pole. The source of this hot h ydrogen is presumably near the position we have found for the density maximum. Therefore we suggest that this source of hot H atoms may be a ssociated either with electroglow or else with the dayside aurora.