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H. T. Smith (Univ. of Virginia), M. Shappirio, E.C. Sittler (NASA GSFC), D Reisenfeld (Univ. of Montana), R.E. Johnson, R.A. Baragiola (Univ. of Virginia), F.J. Crary, D.J. McComas, D.T. Yound (SwRI)
The detection of low energy N+ in Saturn's inner magnetosphere (3.5 < L < 9.5) by the Cassini Plasma Spectrometer (CAPS) is the first evidence for the presence of neutral nitrogen that is locally ionized in this region. This detection was accomplished using CAPS data for the first six orbits. Voyager's detection of unresolved mass/charge 14-16 amu/e ions in this region caused much debate over the possible presence of N+ in Saturn's magnetosphere. Two principal nitrogen sources have been suggested: material from Titan's atmosphere and nitrogen compounds trapped in the icy satellite and ring particle surfaces (e.g., Sittler et al 2004a, b; Smith et al. 2004). The latter may contain primordial nitrogen, likely as NH3 in ice (Stevenson 1982; Squyers et al. 1983) or nitrogen that has been implanted in the surface (Delitsky and Lane 2002). Here we present results supporting N+ detection and show that the immediate nitrogen source is likely to be the icy satellites (Young et al. 2005; Smith et al. 2005a). The strongest spatial correlation of N+ is with Enceladus (Smith et al. 2005b).
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.