four simulations are plotted in Fig. \[fig:PAs\]. For the purpose of these measurements we computed the principal axes for the combined stellar components from both dwarfs in each simulation.

The periods of rotation of the intermediate (and short) axes are 1.7, 2.2, 6.0, and 3.7Gyr for I60R, I90R, I120R, and I90VY1, respectively. The speed of the figure rotation is correlated with the rotation of stellar particles around the long axis (see Fig. \[fig:rot\]) but the particles rotate at a higher speed (at least for the inner 2kpc). Also the direction of the particle rotation is the same as the figure rotation.

The origin of the figure rotation can be traced to the tidal distortion of the disk just before the first encounter. We illustrate this in Fig. \[fig:2maps3d\] which displays stellar density in simulation I90R in three projections along the $Z$, $Y$ and $X$ axis of the simulation box. The upper row shows the projections just before the first passage at 1.95Gyr and the bottom row illustrates the situation soon after the two disks merged, at 5.3Gyr. The upper left panel of the Figure (view along the $Z$ axis) shows the distortion of the disks due to the tidal force 