Low Frequency Waves in the Foreshock of Saturn

BERTUCCI, C.; ACHILLEOS, N.; DOUGHERTY, M. K.; MAZELLE, C.; RUSSELL, C. T.; ROUSSOS, E.; KRIMIGIS, T.; HOSPODARSKY, G.; KURTH, W.; RYMER, A.; YOUNG, D.; TSURUTANI, B.; SMITH, E. J.

Congreso; AGU Fall Meeting 2005; 2005

The study of the physical phenomena in the region upstream from the outer planets provides important information on how key processes in terrestrial space plasma physics such as the formation of quasi-parallel shocks, ion reflection at quasi-perpendicular shocks, particle leakage, etc., operate in plasma environments with high magnetosonic Mach numbers. In this work we study the properties of low frequency electromagnetic waves as seen by the magnetometer onboard Cassini upstream from the bow shock of Saturn with periods between tens of seconds and several minutes. During these events, the prolongation of the local mean magnetic field intersects the mean position of the bow shock suggesting that these waves are generated in the Kronian foreshock. We analyze the polarization and propagation of these waves and also their spatial distribution with respect to the orientation of the interplanetary magnetic field. In addition, we use measurements from other Cassini instruments to try to determine which type of ion distribution is associated with these waves and to infer the instabilities responsible for their generation