Numerical simulation of flare-generated disturbances in the solar wind

The propagation of flare-generated shock waves through the solar wind is examined using numerical solutions of the time-dependent hydrodynamic equations. These solutions are valid for all shock strengths, including the intermediate values that have been observed in the solar wind, and take into account the variation of the properties of the ambient solar wind. The entire range of time scales for energy deposition in the disturbance, from impulsive (producing ‘blast waves’) to continuous deposition, is considered. For the former class of disturbances the solutions approach a limiting form dependent only on the total energy in the wave. Relationships among the energy, shock strength at 1 AU, and transit time to 1 AU are found in the blast wave limit. For disturbances with energies near 1031 ergs, the wave propagates from the sun to 1 AU in ∼60 hours, and is preceded by an intermediate strength shock at the latter distance. Both the transit time and shock strength are in good agreement with directly observed values.