LESIA - Observatoire de Paris

Overview of solar wind interaction at Saturn - from dayside reconnection to kronian substorms

C.M. Jackman (Imperial College, London (UK))

mercredi 6 août 2008, par C.M. Jackman (Imperial College, London (UK))

Mardi 15 juillet 2008 à 11h00

Cassini’s approach to Saturn took place during the declining phase of the solar cycle, while the solar wind was highly structured by compressions and rarefactions associated with corotating interaction regions (CIRs). We discuss here the nature of the heliospheric structure, using data from the Cassini magnetometer. Upon reaching Saturn, we then explore the nature of the solar wind interaction with the planetary magnetosphere. We study the role of dayside reconnection at Saturn’s magnetopause, both with observations and an empirical reconnection voltage formula adapted from Earth.

We then focus on tail reconnection as the completion of the cycle of energization and circulation of plasma in the kronian system, showing in situ examples of plasmoid passage in the magnetotail. While dayside reconnection at Saturn is expected to play a role in the addition of flux to the magnetosphere, the planet’s rapid rotation and internal sources of plasma also drive dynamics. We discuss the relative importance of these factors for triggering magnetotail reconnection. Finally we explore the relationship between the Saturn Kilomteric Radiation (SKR) emissions and kronian tail reconnection events. This problem is approached from a statistical standpoint by applying a thresholding technique, but also from an observational standpoint by examining individual frequency channels of radio emission.

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