Magnetohydrodynamic modeling of the solar wind in the outer heliosphere

A. V. Usmanov, M. L. Goldstein, W. H. Matthaues, and B. Breech  

A magnetohydrodynamic solar wind model is used to simulate the global steady-state structure of the solar wind in the region from 0.3 to 100 AU. The model allows us to vary plasma parameters, such as the plasma beta, and to include the role of heating by the dissipation of turbulence. Also included in the model is the apparent heating of the solar wind by interstellar pickup protons. We compute the variation of plasma temperature in the outer heliosphere and compare it to Ulysses and Voyager 2 observations. The model is based on a self-consistent numerical solution of the combined set of solar wind equations and subgrid-scale turbulence transport equations. We compare the model results with and without turbulence to illuminate the roles of the turbulence cascade and of pickup protons in heating solar wind with heliocentric distance and latitude.