Predicted speed v_WS (left) and radial distance r_WS (right) of the internal WS formed from the interaction between the fast post-eruption stellar wind (1600 km s^-1) with the slower eruption-phase wind (320 km s^-1). Time t = 0 corresponds to the end of the slow-wind phase and is assumed to occur on 1995.1. As the WS advances through the slower wind, it initially travels at a constant speed of 479 km s^-1. After the critical time t_c ≃ 1.4 yr, the WS is accelerated asymptotically approaching the fast wind velocity.