Le satellite Encelade source d'ions N+ dans la magnétosphère de Saturne

The first pass of the Cassini probe in the vicinity of Saturn, above the E-ring, demonstrated a plasma consisting of water group ions (H+, O+, OH+, H2O+) with a small N+ ion component (3%). Using a simple model for the transport of magnetospheric ions, we show that the N+ ions can be traced back to the Enceladus satellite. Such a result can be explained by the existence in this icy satellite, supposed to be still geologically active, of volatile components such as ammonia NH3, or by the previous implantation of N+ ions of external origin on its surface. To cite this article: M. Bouhram et al., C. R. Physique 6 (2005).