37th DPS Meeting, 4-9 September 2005
Session 58 Galilean Satellites
Poster, Thursday, September 8, 2005, 6:00-7:15pm, Music Recital Room

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[58.11] Close-up Imaging of Sodium Escaping from Io

M. Mendillo, J.K. Wilson, S. Laurent, J. Baumgardner (BU/Center for Space Physics)

The heavy ion population in Jupiter's magnetosphere is ultimately supplied by volcanic activity on Jupiter's moon Io. Gasses emitted from the volcanoes form a tenuous atmosphere around Io. This atmosphere, in turn, escapes from Io and is ionized, forming the plasma torus around Jupiter.

One of the uncertainties regarding Io's atmospheric escape is the spatial distribution of the escape flux over Io. From observations of the large-scale neutral clouds around Io, it is believed that atmospheric sputtering results in a nearly isotropic, slow outflow of neutrals. On the other hand, the high-speed sodium "jet" is believed to arise from ionospheric escape from Io's anti- Jovian hemisphere. The source location of the dissociating molecular pickup ion stream is more difficult to deduce since the molecular ions in question travel downstream of Io for hours before dissociating into neutrals which can be detected.

In order to localize the source regions around Io, we have used the 3.7-meter AEOS telescope on Mt. Haleakala to take spectral images of sodium emission within a few Io radii of Io. Preliminary analysis of data from December 2000 indicates that the highest neutral sodium densities were found downstream of Io, where we would expect to find the beginning of the dissociating molecular ion stream.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.