Brown, Michael E. (1995) Periodicities in the Io plasma torus. Journal of Geophysical Research A, 100 (A11). pp. 21683-21695. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20121002-101425791
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We present a 6-month baseline of spatially resolved measurements of the Io plasma torus intensity and perpendicular ion temperature which we use to determine the periodicities of the torus during this time. We find large anticorrelated variations in the intensity and ion temperature which are periodic with the Jovian rotation rate (System III). The intensity variations are found to be a simple manifestation of the temperature variations, though no explanation for the temperature variations is apparent. Periodogram analysis shows an additional intensity periodicity which rotates 2.91±0.06% more slowly than System III. This period is found only in the intensity and not in the ion temperature. We conclude from these observations that the torus has a sinusoidal ion temperature variation locked into the rotation of Jupiter and that superimposed on this is a long-lived density pattern which rotates 2.91% more slowly than Jupiter. Based on the spatial structure and physical properties, we rule out all currently proposed mechanisms for the creation of these periodicities within the torus.
|Additional Information:||© 1995 American Geophysical Union. Received 31 January 1995; accepted 23 June 1995. I would like to thank Lick Observatory for the generous grant of substantial observing time. The Lick staff, and Tony Misch in particular, provided crucial assistance during the course of these observations. Many people have helped shape the course of this research, including Fran Bagenal, Alex Dessler, Mike Kaiser, Melissa McGrath, Imke de Pater, Frank Scherb, Nick Schneider, Bill Smyth, and Hy Spinrad. This research was supported, in various stages, by a grant from Calspace, by a NASA graduate fellowship, and by NASA through grant number HF-1056.01-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5- 26555. The Editor thanks N.M. Schneider and another referee for their assistance in evaluating this paper.|
|Official Citation:||Brown, M. E. (1995), Periodicities in the Io plasma torus, J. Geophys. Res., 100(A11), 21,683–21,695, doi:10.1029/95JA01988.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||02 Oct 2012 17:44|
|Last Modified:||27 Dec 2012 02:47|
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