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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 3 | Copyright
Ann. Geophys., 36, 831-839, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

ANGEO Communicates 07 Jun 2018

ANGEO Communicates | 07 Jun 2018

On the location of the Io plasma torus: Voyager 1 observations

Martin Volwerk Martin Volwerk
  • Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria

Abstract. The Voyager 1 outbound ultraviolet observations of the Io plasma torus are used to determine the location of the ansae, to obtain a third viewing angle of this structure in the Jovian magnetosphere. At an angle of −114° with respect to the Sun–Jupiter line, or a Jovian local time of 04:30LT, the Voyager 1 data deliver a distance of 5.74±0.10RJ for the approaching and 5.83±0.15RJ for the receding ansa. Various periodicities in the radial distance, brightness and width of the ansae are seen with respect to system III longitude and Io phase angle. The torus ribbon feature does not appear in all ansa scans.

Publications Copernicus
Short summary
Using Voyager 1 observations of Jupiter's Io plasma torus, we have determined the location of maximum brightness depending on longitude and the location of Jupiter’s moon Io. We obtain a third viewing direction of the torus (after Voyager 2 and ground observations) and thus two locations, left and right of Jupiter, which are important for the correct modeling of this structure. We also find that a narrow ribbon-like structure only appears when the brightness of the torus exceeds a certain value.
Using Voyager 1 observations of Jupiter's Io plasma torus, we have determined the location of...