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K.D. Retherford, H.W. Moos, D.F. Strobel, B.C. Wolven (JHU), R.J. Oliversen (GSFC)
Recent observations of Io with HST/STIS (Roesler et al., Science 283, 353, 1999) revealed bright equatorial regions of UV emission. Models of the sub-Alfvenic interaction between Jupiter's magnetosphere and Io's neutral atmosphere suggest that the location and general shape of these UV emitting regions are a natural consequence of this interaction (Saur et al., AGU meeting, Fall 1998, Linker et al., AGU meeting, Fall 1998). We present a detailed characterization of the location, shape, and brightness of these emission regions imaged with STIS in both 1997 and 1998. This information is valuable for studying the detailed nature of the electrodynamic interaction between Io's atmosphere and the local plasma flow. Of note, the locations of the emission regions are strongly correlated with the jovian magnetic field orientation at Io. Also, the brightness of the emissions in this data set appears to be correlated with Io's distance from the plasma torus centrifugal equator. No direct correlation is seen, however, between the location of the UV emission and the location of active volcanos and hot spots on Io's surface, in contrast with the results obtained from Galileo SSI images of visible emissions from Io in eclipse (Geissler et al., DPS meeting, 1998).
The author(s) of this abstract have provided an email address for comments about the abstract: reth@jhu.edu