Understanding the motion and source of the plasma around Saturn is important for understanding the dynamics of the magnetosphere. Pontius and Hill present a theory that describes plasma transport in Saturn's magnetosphere, including processes that add new mass to the plasma and those that remove momentum from the plasma without changing plasma mass.
Using observational data from the Cassini spacecraft on the angular velocity of plasma around Saturn along with chemistry models of Saturn's magnetosphere, the authors calculate the distribution of new mass entering the magnetosphere.
They confirm that most of the plasma comes from a neutral gas region near the orbit of Saturn's moon Enceladus and quantify the rate at which plasma mass is added to the magnetosphere from this region. The distribution and source of mass addition is important because it affects the rotation rate of the magnetosphere.
The work provides a new method of analysis that could be useful for future studies.
The research is published in Geophysical Research Letters. Authors include D. H. Pontius Jr.: Department of Physics, Birmingham-Southern College, Birmingham, Alabama, USA; and T. W. Hill: Department of Physics and Astronomy, Rice University, Houston, Texas, USA.
- Pontius et al. Plasma mass loading from the extended neutral gas torus of Enceladus as inferred from the observed plasma corotation lag. Geophysical Research Letters, 2009; 36 (23): L23103 DOI: 10.1029/2009GL041030
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