Observation of similar radio signatures at Saturn and Jupiter: Implications for the magnetospheric dynamics.

P. Louarn (1) , W.S. Kurth (2) , D.A. Gurnett (2) , G.B. Hospodarsky (2) , A.M. Persoon (2) , B. Cecconi (3) , A. Lecacheux (3) , P. Zarka (3) , P. Canu (4) , A. Roux (4) , H.O. Rucker (5) , W.M. Farrell (6) , M.L. Kaiser (6) , N. Andre (7) , C. Harvey (1) , M. Blanc (1)

1 CESR - Centre d'étude spatiale des rayonnements
2 Department of Physics and Astronomy, University of Iowa
3 OP - Observatoire de Paris - Site de Paris
4 CETP - Centre d'étude des environnements terrestre et planétaires
5 IWF - Space Research Institute of Austrian Academy of Sciences
6 GSFC - NASA Goddard Space Flight Center
7 ESTEC - European Space Research and Technology Centre

We report on radio signatures observed at Saturn by the Cassini RPWS experiment which are strikingly similar to the Jovian “energetic events” observed by Galileo. They consist of sudden intensifications of the auroral radio emission (SKR) followed by the detection of a periodic narrowband radiation which most likely originates from Saturn's plasma disk. About ten “events” have been observed in 2006, showing on average temporal scales ∼3 times longer than their Jovian counterparts. We analyze the conditions of generation and the visibility of the narrowband radiation and conclude that the Kronian “events” are most likely associated with plasma evacuation from the disk. These observations provide new insights on the role of internal energy releases in Saturn's magnetosphere, known from other observations to be mainly driven by the solar wind.

Keywords: planetary magnetosphere; Saturn; plasma waves

Domains: Astrophysics [astro-ph]; Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]

P. Louarn, W.S. Kurth, D.A. Gurnett, G.B. Hospodarsky, A.M. Persoon, et al.. Observation of similar radio signatures at Saturn and Jupiter: Implications for the magnetospheric dynamics.. Geophysical Research Letters, 2007, 34 (20), pp.L20113. ⟨10.1029/2007GL030368⟩. ⟨hal-00153869⟩