A tilted-dipole MHD model of the solar corona and solar wind

Arcadi V. Usmanov, Melvyn L. Goldstein, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA

We simulate the heliospheric structure during solar activity minimum as determined by boundary conditions at the coronal base and compare output from the model with Ulysses observations during its first fast latitude transition in 1994-1995. The polytropic MHD equations are solved for a steady coronal outflow and include Alfvén wave momentum and energy addition in the WKB approximation. A solution for the outflow in a tilted dipole magnetic field in the inner computational region (1-20 $R_{\sun}$) is combined with a three-dimensional solution in the outer region which extends to 10~AU. The dipole orientation is chosen to match the one inferred from observations during the Ulysses observations. The bimodality of solar wind with a rapid change in flow parameters with latitude and the observed extension of the slower wind belt are reproduced fairly well.