GROUND-BASED OBSERVATION OF VISIBLE AURORA ON JUPITER BY SPECTROSCOPIC IMAGING WITH NARROW BANDPASS

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1. Detailed examination of observation results on Jupiter visible aurora obtained at Okayama Astrophysical Observatory with High Dispersion Echell Spectrograph (HIDES) coupled with a 188-cm telescope revealed marginal (S/N〜1) detection of Hα aurora in the southern polar region of Jupiter.2. Based on detailed analysis of observation results obtained at Mt.Haleakala using a Fabry-Perot interferometer in 2004 and 2005, two-dimensional distributions of sulfur ion emission intensity, bulk velocities of sulfur ions and their deviation from the corotation velocity in Io plasma torus were obtained as well as ion temperatures perpendicular and parallel to the magnetic field line. From these results, it became clear that plasma supply to the Io torus is considerably uniform in a region away from Io, and that its amount is variable from year to year. In addition, resonant scattering of sodium atoms in the close proximity to Io was observed by using the Fabry-Perot interferometer coupled to a 3.7m AEOS telescope. Detailed analysis of the data showed that distribution of sodium atoms are asymmetric with respect to Io's Jupiter side and anti-Jupiter side.3. Based on observation of resonant scattering of Iogenic sodium atoms and computer simulation, sputtering and dissociation and dissociative recombination of molecular ion are found to be the dominant processes for producing high-velocity sodium atoms.