Volume rendering of the ejecta structure of the pure merger product without the surrounding envelope, colour-coded by density. The respective direction of the x-, y-, and z-axis is shown in a small diagram at the top of the rendering, next to the colour bar, as a red, green, and blue line. The coloured lines in the rendered volume illustrate three of the viewing angles used as input for the radiative-transfer simulations with STELLA performed in this work. The dark green line 045 000 is located in the x − y plane (orbital plane of the progenitor system), the light blue 000 050 and yellow 000 040 lines are both located in the x − z plane (perpendicular to the orbital plane of the progenitor system).