Initial Cassini Observations of the Shape of Saturn's Magnetopause

ACHILLEOS, N.; ARRIDGE, C. S.; BERTUCCI, C.; DOUGHERTY, M. K.; KHURANA, K. K.

Congreso; American Astronomical Society, DPS meeting #37; 2005

Theoretical and empirical models have been constructed to represent Saturn´s magnetopause. A Newtonian pressure balance condition has been applied to derive solar wind dynamic pressure at each of the magnetopause crossings observed in the first few orbits of Saturn by the Cassini spacecraft. We examine the relation between standoff distance RN (distance from Saturn to magnetopause ´nose´) and solar wind pressure PSW, for assumed magnetopause shape models. Interestingly, a new magnetopause shape, derived using the Cassini data and the Shue et al (1997) functional form, indicates a power law scaling RN PSW j with j between 1/4 and 1/5 - reflecting a ´magnetodisc´-like configuration for Saturn. The derived models are then applied to the Cassini orbits in their entirety, in order to produce probability distributions of the magnetopause standoff distance (indicative of size) and corresponding PSW value.