Saturn's UV Aurora Imaged with HST during the Cassini Approach to Saturn

Poster (2004, December 13)

A series of HST STIS UV images of Saturn's aurora were obtained on 13 days in Jan. 2004 as the Cassini spacecraft measured the approaching solar wind properties. Clear general correlations have been found ... [more ▼]

A series of HST STIS UV images of Saturn's aurora were obtained on 13 days in Jan. 2004 as the Cassini spacecraft measured the approaching solar wind properties. Clear general correlations have been found between the auroral power and a) Saturn's kilometric radiation, and b) the solar wind dynamic pressure, but not with the direction of the interplanetary magnetic field. While these general correlations are now well established, a closer examination of the data raises many interesting questions. Saturn's auroral emissions exhibit both local time and co-rotational properties, the auroral oval does not appear centered on the magnetic and rotational pole, the auroral emissions exhibit large and unexpected motions in latitude with time and/or planetary rotation, and the auroral oval does not appear continuous, but broken with longitude. This talk will present a more detailed look at Saturn's aurora from the HST images, with a comparison of auroral emission properties to those at the Earth and Jupiter. [less ▲]

HST STIS Observations of Saturn's Auroral Variations Concurrent with the Cassini Solar Wind Campaign in Jan. 2004

Conference (2004, May 17)

Saturn's magnetosphere is often referred to as "intermediate between the cases of the Earth and Jupiter". Due to very limited measurements of Saturn's magnetosphere and auroral activity, however, it has ... [more ▼]

Saturn's magnetosphere is often referred to as "intermediate between the cases of the Earth and Jupiter". Due to very limited measurements of Saturn's magnetosphere and auroral activity, however, it has never been clear in detail what this statement means. A recent campaign of HST STIS UV imaging of Saturn's aurora has been carried out over 8-30 Jan. 2004 concurrent with measurements of the approaching solar wind by Cassini. This imaging set is much more comprehensive than any earlier observations of Saturn's aurora, obtained at a time when Saturn's southern auroral oval is completely visible due to the large apparent tilt of Saturn. The data provide the opportunity to determine the mean distribution of the auroral emissions, the degree of corotation of any bright regions, any variations with local time of the emissions, the latitudinal motions of the main oval with time and location, and other parameters. In addition, each of these can be compared with the approaching solar wind conditions and Saturn's kilometric radiation (SKR) intensity from Cassini measurements. Quick looks at the data from HST and Cassini demonstrate that the measurements have been made successfully, and the coverage includes dramatic variations in Saturn's auroral activity as well as at least two solar wind shocks passing Cassini. This presentation will concentrate on the measured properties of Saturn's aurora in the context of comparisons with the magnetospheres of the Earth and Jupiter. [less ▲]