of the surface distributions of the stars (such as those shown in the left column of Fig. \[fig:maps\]) for all simulations. The amplitude of the $m$th Fourier mode is given as $A_m = (1/N) \left| \Sigma^{N}_{j=1} \exp (i m \phi_j) \right|$ where $\phi_j$ are the particle phases in the projection plane and $N$ is the total number of particles. It turns out that over the last few Gyr of evolution $A_4\approx 0.06$ for I60R while it is at least a factor of two lower for the other simulations. This shape must originate from the orbital structure of the merger remnant and we discuss this issue further in the following sections.

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Orbital structure
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Figure rotation
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Although the ratios of principal axes do not vary significantly over the last 5Gyr for all simulations, all but I90VY2 show clear figure rotation around the major $x$ axis. The orientation of the major axis remains stable for the whole period of 5Gyr and it coincides with the collision ($X$) axis for radial mergers and is inclined by 22deg from the collision axis for I90VY1 but remains in the $XY$ plane. The evolution of the position angles of the intermediate axes for these 