Fig. 10 a-d. Equatorial density contours showing the long term evolution of the binary system, as calculated with code TREESPH using 13997 particles. The contour lines correspond to the logarithm of the density. The high- and low-density values are labeled. Counterclockwise rotation is assumed. A sequence in time is presented: a (upper left) , b (upper right) , c (lower left) , and d (lower right) . A region of radius cm is shown. The binary separation distance in terms of is 0.22, 0.16, 0.12, and 0.09 in a, b, c, and d, respectively.