A Data-driven Model of the Solar Wind, Interstellar Pickup Ions, and
Turbulence throughout Interplanetary Space
Abstract
The outer heliosphere is an interesting region characterized by the
interaction between the solar wind and the interstellar neutral atoms.
Having accomplished the mission to Pluto in 2015 and currently on the
way to the Kuiper Belt, the New Horizons spacecraft is following the
footsteps of the two Voyager spacecraft that previously explored this
region lying roughly beyond 30 AU from the Sun. We model the
three-dimensional, time-dependent solar wind plasma flow to the outer
heliosphere using our own software Multi-Scale Fluid-Kinetic Simulation
Suite (MS-FLUKSS), which, in addition to the thermal solar wind plasma,
takes into account charge exchange of the solar wind protons with
interstellar neutral atoms and treats nonthermal ions (i.e., pickup
ions) born during this process as a separate fluid. Additionally,
MS-FLUKSS allows us to model turbulence generated by pickup ions. We use
MS-FLUKSS to investigate the evolution of plasma and turbulent
fluctuations along the trajectory of the New Horizons spacecraft using
plasma and turbulence parameters from OMNI data as time-dependent
boundary conditions at 1 AU for the Reynolds-averaged MHD equations. We
compare the model with in situ plasma observations by New Horizons,
Voyager 2, and Ulysses. We also compare the model pickup proton
parameters with those derived from the Ulysses-SWICS data.