Dynamics of the Interplanetary Gas and Magnetic Fields.

We consider the dynamical consequences of Biermann's suggestion that gas is often streaming outward in all directions from the sun with velocities of the order of 500-1500 km/sec. These velocities of 500 km/sec and more and the interplanetary densities of 500 ions/cm3 (1014 gm/sec mass loss from the sun) follow from the hydrodynamic equations for a 3 X 1060 K solar corona. It is suggested that the outward-streaming gas draws out the lines of force of the solar magnetic fields so that near the sun the field is very nearly in a radial direction. Plasma instabilities are expected to result in the thick shell of disordered field (10- gauss) inclosing the inner solar system, whose presence has already been inferred from cosmic-ray observations.