Asymmetric propagation of flare‐generated shocks in the heliospheric equatorial plane

Abstract

A numerical simulation study is presented in this paper in terms of a two‐dimensional, two‐component MHD model, concerning the propagation of flare‐generated shocks in the heliospheric equatorial plane. The numerical results show that the spiral interplanetary magnetic field and the heliospheric plasma sheet in the equatorial plane have a significant influence on the shock propagation. When the shock source lies east of the heliospheric current sheet (HCS) within a longitudinal distance of 50°∼70°, depending on the shock strength, the fastest propagation direction of the shock deflects eastward from the flare normal by an angle that increases with the initial shock strength and decreases with the distance between the shock source and the HCS. On the other hand, if the shock source lies west of the HCS within a longitudinal distance of 30°, the fastest propagation direction of the shock deflects westward from the flare normal by an angle that decreases with both the initial shock strength and the distance between the shock source and the HCS. For shocks whose source is far away from the HCS their fastest propagation direction always deflects westward from the flare normal, and the deflection angle decreases with the initial shock strength and does not depend on the source position. The theoretical predictions are compared with the conclusions reached by data interpretation of the propagation of flare‐generated shocks in the heliospheric equatorial plane.