Shapes of strong shock fronts in an inhomogeneous solar wind

The shapes expected for solar-flare-produced strong shock fronts in the solar wind have been calculated, large-scale variations in the ambient medium being taken into account. A linear mathematical model was used, based on the assumptions that (1) the pressure immediately behind a shock front is constant over the surface of the front, (2) the variations in the ambient medium are time stationary in a frame of reference corotating with the sun, and (3) the effects of the interplanetary magnetic field can be neglected. The shock fronts were assumed to be spherically symmetric near the sun. It has been shown that for reasonable ambient solar wind conditions the mean and the standard deviation of the east-west shock normal angle are in agreement with experimental observations including shocks of all strengths. The results further suggest that near a high-speed stream it is difficult to distinguish between corotating shocks and flare-associated shocks on the basis of the shock normal alone. Although the calculated shapes are outside the range of validity of the linear approximation, these results indicate that the variations in the ambient solar wind may account for large deviations of shock normals from the radial direction.