A Simulation Study of the Interaction Between a Fast Shock and the Heliopuase

Abstract

In a one-dimensional hybrid simulation of a fast shock impinging on the heliopause (HP), it is found that two regions of increased plasma density are formed between the transmitted and reflected shocks. The region downstream of the shock, on the interstellar side of the heliopause, has typically twice the original plasma density. The density increase is dependent on the impinging shock speed. This region has a greatly enhanced ion temperature anisotropy T(subscript ┴)/T(subscript ∥)-100 and a plasma beta β~0.1-1.0, which may lead to the generation of ion cyclotron waves and mirror waves. The region downstream of the reflected shock, on the solar wind side of the heliopause, has typically a 25% increase in plasma density. The enhanced temperature anisotropy is T(subscript ┴)/T(subscript ∥)~1.2, but the plasma beta is very high, β-20, which may also lead to the generation of mirror waves and ion cyclotron waves.