Motion of the heliospheric termination shock: 3. Incident interplanetary shocks

In this paper the response of the heliospheric termination shock to an incident interplanetary shock is examined. This paper is an extension of a recent study by Barnes (1993), which treated the analogous problem for an incident contact discontinuity. The termination shock is treated as a strong gasdynamic shock. The postinteraction configuration consists of a moving termination shock, a postshock contact discontinuity, and either a shock or rarefaction wave propagating the disturbance signal into the downstream medium. For a decrease in dynamic pressure a rarefaction wave propagates downstream, and the new termination shock propagates inward, while for an enhancement of dynamic pressure the termination shock moves outwards and a weak outer shock propagates into the downstream medium; speeds of motion of the termination shock are typically of the order of ∼100 km/s. The results are similar to those presented by Barnes (1993) indicating that the results of that paper are robust within the gasdynamic model, in the sense of being independent of the details of the initial disturbance.