Serial optical observation of Jovian plasma processes at the summit of Mauna Kea in Hawaii

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The study, 2-dimensional imaging observations of the D-line emission distribution of logenic sodium atoms, which is regarded as a tracer of logenic volcanic gases, were performed with two field of views (FOV), namely±20Rj (narrow FOV ; Rj : Jovian radius), and ±400Rj (wide FOV). From the observational results, the following characteristics of emission distribution were obtained. In the narrow FOV observation, two different types of distribution extending to〜20Rj, that is, the band-shaped distribution and the spray-shaped distribution, were observed simultaneously. In the wide FOV observation, the elongated oval-like emission distribution extended to as much as 400Rj along the equatorial plane was observed. The east-west intensity asymmetry was also observed, with a dependence on the Io phase angle.Based on the observed images , we then made model analyses to investigate supply processes of sodium atoms and time variation of sodium distribution, and presented the comprehensive source process which can consistently reproduce the observed characteristics both in the narrow and wide FOV observation.From the model analysis for the narrow FOV observational results, it is concluded that the band-shaped distribution is attributed to the molecular ion destruction process, and the typical gyrovelocity of the molecular ions is estimated to be 20km/sec. It is also concluded that the spray-shaped distribution is produced through the charge exchange process. Then a combination of the two processes was examined for the wide FOV observational results. The combined model analysis could fairly reproduce the observed features of the wide extended sodium distribution. In the course of the model analysis, some important physical processes and related parameters are suggested.