Kinetic modeling of the composition and dynamics of volatile’s distribution in Europa’s exosphere

Abstract:

The surface-bound Europa’s exosphere is tightly connected to both the Jovian magnetosphere as well as to Europa’s icy surface. The neutral species in the exosphere are mostly produced by the Jovian magnetospheric ion sputtering of the water ice surface and direct ejection from Europa’s plume.

Here, we present results of our model study of the distribution of the neutral species in Europa’s exosphere, their escape and migration over the moon’s surface. The work is a part of a more global effort aimed at fully coupled understanding of the interaction between Europa’s exosphere and Jovian magnetosphere.

The modeled neutral species are produced via sputtering (O₂ and H₂O), directly ejected into the plume (H₂O), or produced via photolytic or electron impact reactions (OH, O₂, O, H). The computational domain extends to altitudes up to ~10 R_E, which exceeds the radius of Europa’s Hill sphere (~8.5 R_E, Miljkovic et al., 2012). Jupiter’s and Europa’s gravity are taken into consideration. The modeling is performed using our kinetic Adaptive Mesh Particle Simulator (Tenishev et al., 2013), where the exospheric species are represented by a large set of the model particles governed by the same physical laws as those of the real exosphere. The calculated HI and OI brightness synthetic images are compared with those obtained with Hubble Space Telescope (Roth et al., 2014).