Conditions at the magnetopause of Saturn and implications for the solar wind interaction

摘要

Using idealized models of the magnetosheath and magnetospheric magnetic fields, plasma densities, and plasma flow, we test for the steady state viability of processes mediating the interaction between the solar wind and the magnetosphere of Saturn. The magnetopause is modeled as an asymmetric paraboloid with a standoff distance of ～25 RS. We test where on the magnetopause surface large-scale reconnection may be affected by either a shear flow or diamagnetic drift due to a pressure gradient across the magnetopause boundary. We also test for the onset of the Kelvin-Helmholtz instability. We find that, for the solar wind and magnetosphere states considered, reconnection is inhibited on the dawn flank due to the large shear flows in this region. Additionally, most of the dawn and dusk equatorial region of the magnetopause is Kelvin-Helmholtz unstable, due to the presence of the dense magnetospheric plasma sheet and weak magnetic fields on either side of the magnetopause. This study is a follow-up to a previously published study of the solar wind interaction with Jupiter's magnetosphere. Key Points Velocity shears limit reconnection on Saturn's dawn flank. Diamagnetic drifts may limit reconnection but depend on energetic population. The dawn flank of Saturn's magnetopause is Kelvin-Helmholtz unstable.