Left column: rest-mass density after 60 and 180d for a recoil velocity V_k = 500 km s^-1 applied to model L.00. The scale is logarithmic and expressed in cgs units. Right column: shock structure as presented in Fig. 1 for the same panels in the left column. Once again we remark that is very hard to locate a shock by simply looking at the density distribution, especially when they are very weak (here we have used χ = 0 in Eq. (30)). Note also that the temperature distribution is inversionally proportional to that of the density (not shown here).