March 5, 2010, 12:00 pm - 1:00 pm
March 5, 2010, 12:00 pm - 1:00 pm
Understanding the interaction between Mercury and Saturn with the solar wind: combining multi-fluid simulations and observations
Ariah Kidder (University of Washington)
The small and large systems of Mercury and Saturn allow study of how space plasmas interact with planetary magnetospheres. Mercury is the smallest planet in the solar system and has a weak magnetic field, yet experiences the intense solar wind in its orbital location as the innermost planet. Saturn’s large magnetosphere is dominated by a source of cold heavy ions: Enceladus, an icy moon deeply embedded in Saturn’s inner magnetosphere. A plume of ice and water vapor recently discovered emanating from its south pole creates a torus of particles near the moon and centered on its orbit. Observations made in both systems drive ongoing research into the interaction of these two magnetospheres with the solar wind. I integrate ground-based observations of Mercury as well as compare to measurements from the MESSENGER and Cassini spacecraft, to clarify data and develop a global three-dimensional picture of these two magnetospheres. In order to understand the role heavy ions and magnetic reconnection play in these two systems, we use a three-dimensional multi-fluid model that incorporates different ion species and gyroradius effects. Multi-fluid simulations resolve the plasma dynamics in the cross-tail current sheet, while providing a global treatment of the magnetosphere and the outflow of plasma. The results from the multi-fluid treatment are well correlated with observations of flux rope formation at Mercury and plasma injections in Saturn’s inner magnetosphere. Heavy ion gyromotion plays an important role in governing the shape and dynamics of these two magnetospheres. Model output also serves to clarify the relative importance of internal conditions (e.g. sources of heavy ions) versus upstream control (e.g. the effects of solar wind or interplanetary magnetic field) to plasma processes at both planets.