Low-latitude H Lyman-alpha emissions from the Galileo Ultraviolet Spectrometer

W.K. Tobiska (Nyma/Telos/JPL), W.R. Pryor (LASP/Univ. of Colorado), G.R. Gladstone (SwRI), C. Hord (LASP/Univ. of Colorado), J. Ajello (JPL)

The processes contributing to the detailed formation of H Lyman-alpha emission in Jupiterís upper atmosphere at low latitudes are still not thoroughly known although resonant scattering of solar H Lyman-alpha photons, charged particle collisional excitation of H, dissociative exitation of H2, and hydrogenic ion recombination (H+ or H3+) have been proposed. The Galileo Ultraviolet Spectrometer (UVS) has systematically observed Jupiterís low latitude hydrogen Lyman-alpha during the first half of the prime mission. Observations from orbits G1 through G8 have provided a preliminary mapping of the Lyman-alpha distribution for most System III longitudes. These observations provide a database for examining the contribution of many of the formation mechanisms because emissions related to solar and non-solar processes are separately observed away from the auroral zones across most longitudes and for most emission angles. The Galileo UVS H Lyman-alpha data are shown and possible production mechanisms are suggested for the observed emissions.