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 Jupiter�s 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 Jupiter�s 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.