IDEALIZED SATURN MAGNETOSPHERE SHAPE AND FIELD

We construct an idealized three-dimensional model of Saturn's magnetos phere. The total magnetospheric field is a sum of three contributions; the first two contributions are internal, in the form of a planetary dipole and an equatorial ring current deduced from Voyager observation s. We concentrate on the third contribution, resulting from the intera ction of the solar wind with the Kronian magnetosphere. From the balan ce between the solar wind ram pressure and the magnetospheric pressure , we provide simultaneously models of the magnetopause and of the magn etic field due to the surface currents on the magnetopause. The result ing magnetopause has characteristics intermediate between those of ana logous Earth and Jupiter magnetospheric models. A natural day-night as ymmetry arises in the total magnetospheric field. Its intensity is tes ted with Voyager 1 data: the third contribution improves the agreement between data and models in the outer magnetosphere. This work extends the range of, physically reliable model of Saturn's magnetosphere in latitudinal and longitudinal directions from regions where there have been observations to regions where there have not. We discuss several possible applications, particularly some relevant to the future Cassin i mission.