A 3D MHD Solar Wind Model with Pickup Protons
Arcadi V. Usmanov, Melvyn L. Goldstein, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
We have developed a three-dimensional steady-state MHD model of the solar corona and solar wind. The model covers the region from the coronal base to 100 AU and accounts for the effects of pickup protons in the distant heliosphere. To attain these ends, the two-region model of Usmanov and Goldstein  was modified to become fully three-dimensional and to include a region III that extends from 1-100 AU and incorporates a population of interstellar pickup protons and its interaction with the solar wind protons. Following the approach of Isenberg  and Whang , we consider the solar wind outside 1~AU as a combination of three comoving species -- solar wind protons, electrons, and pickup protons -- and solve the MHD equations with source terms due to photoionization and charge exchange. Separate energy equations are included for solar wind and pickup protons. We compute the global structure of the solar wind from the coronal base out to 100 AU, compare the results with Ulysses and Voyager~2 observations, and present a study of the effects of the pickup protons on solar wind properties.