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Originally published in Science Express on 22 March 2007
Science 20 April 2007:
Vol. 316. no. 5823, pp. 442 - 445
DOI: 10.1126/science.1138562
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Reports

The Variable Rotation Period of the Inner Region of Saturn's Plasma Disk

D. A. Gurnett,1 A. M. Persoon,1 W. S. Kurth,1 J. B. Groene,1 T. F. Averkamp,1 M. K. Dougherty,2 D. J. Southwood2,3

We show that the plasma and magnetic fields in the inner region of Saturn's plasma disk rotate in synchronism with the time-variable modulation period of Saturn's kilometric radio emission. This relation suggests that the radio modulation has its origins in the inner region of the plasma disk, most likely from a centrifugally driven convective instability and an associated plasma outflow that slowly slips in phase relative to Saturn's internal rotation. The slippage rate is determined by the electrodynamic coupling of the plasma disk to Saturn and by the drag force exerted by its interaction with the Enceladus neutral gas torus.

1 Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA.
2 Blackett Laboratory, Imperial College, London SW7 2AZ, UK.
3 European Space Agency, 75738 Paris, France.

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Saturn's Gravitational Field, Internal Rotation, and Interior Structure.
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