The response of a gasdynamic termination shock to interplanetary disturbances

Abstract

A one‐dimensional gasdynamic model is used to analyze the interaction of the solar wind termination shock (TS) with various interplanetary disturbances. These include density enhancements and depletions, Gaussian “shock” pulses, and forward‐reverse shock pairs. Our simulations suggest that the termination shock is unlikely to be stationary. Both the interaction state and the postinteraction state of the termination shock are discussed. The very complicated state and structure of the TS during interaction with interplanetary disturbances is examined carefully. It is found that the TS is not readily identifiable from the other simultaneously present structures (reverse shock, contact discontinuities, forward shocks and so on.). This may complicate the identification of the TS by the Voyager or Pioneer spacecraft significantly. It is also found that a number of interesting structures propagate and evolve downstream after a collision. These include sharp spikes in the density, which advect outward at the postshock flow speed, and secondary damped shock pulses produced in the collision, which propagate supersonically. Some implications of both the density enhancements and the production of damped shock waves in the heliosheath and at the heliopause are discussed.