An assessment of magnetic reconnection at Saturn's magnetopause

Magnetic reconnection is an important process that occurs at the magnetopause boundary of Earth's magnetosphere because it leads to transport of solar wind energy into the system, driving magnetospheric dynamics. However, the nature of magnetopause reconnection in the case of Saturn's magnetosphere is unclear, and has been the subject of debate. Here we use a global magnetohydrodynamic simulation of Saturn's magnetosphere as a basis for assessing when and where reconnection is likely to occur on the Saturnian magnetopause. We extract conditions adjacent to the modeled magnetopause boundary, compare to Cassini spacecraft observations, and apply current understanding of the conditions required for reconnection onset. We discuss the influence of bulk flow shears and local plasma β conditions on magnetopause reconnection, including their anticipated effect on the reconnection rate. Both these factors are expected to have a negative influence on the reconnection process at Saturn's magnetopause, compared to reconnection at Earth's magnetopause. Our results imply that the nature of solar wind-magnetosphere coupling via reconnection can vary between planets, and we should not assume that the nature of this coupling is always Earth-like.