Two snapshots of the coalescing CG: when identified (top) and at present (bottom). This is the only group studied for which all members merge into a single galaxy before z = 0. The purple circles indicate the four members of the CG, while other dark regions indicate dwarf galaxies that do not have a stellar mass similar to the members of the CG. This CG_z = 0.23 is the result of a close encounter between two pairs of galaxies: the two at the left (X ≈ −50 kpc), and the two at the right (X ≈ 60 kpc), which are very close in projection and show some signs of tidal interaction. Darker colours indicate a higher number density of particles. Images were generated with the Py-SPH Viewer library (Benítez-Llambay 2017).