Simulation of a coronal streamer: Alfvén wave acceleration

Abstract

A self-consistent simulation of the plasma flow in a dipole-like magnetic field configuration is performed. The features of the present formulation are: incorporation of the heat and momentum addition due to WKB Alfvén waves propagating outward from the Sun and providing additional acceleration to the coronal plasma flow; extension of the computational domain out to 1 AU. The governing dissipationless single-fluid MHD equations are solved in the equatorial plane of the spherical coordinate system. In agreement with Ulysses observations, the results of simulation demonstrate (i) absence of a marked gradient in the radial magnetic field distribution across the polar high-velocity stream, (ii) the velocity does not change considerably in this stream, but slightly increases toward its center, (iii) the momentum flux density is higher over the pole than near the equator, while the mass flux density shows a slight increase toward the equator.