GASDYNAMIC MODELS OF THE SOLAR-WIND INTERSTELLAR-MEDIUM INTERACTION

The interaction between the solar wind and the interstellar medium is modeled self-consistently using numerical solutions of the time-depend ent gasdynamic equations in spherical and cylindrical coordinates. For the results presented here it is assumed that the solar system moves through the surrounding medium with a supersonic velocity. After an in itial (nonequilibrium) state has been specified, the numerical solutio n follows the evolution in time until the interaction relaxes to a dyn amic equilibrium. As would be expected, the solutions show the formati on of a bow shock upstream of the traveling solar system to deflect th e interstellar plasma around the cavity created by the solar wind. A t ermination shock also forms to slow and compress the solar wind plasma . For the simulation in spherical coordinates, the downstream portion of the termination shock reaches equilibrium more than three times fur ther from the Sun than the equilibrium distance to the termination sho ck on the upstream side.