Representation of BSS grid. The x-axis and y-axis report all the different values of M₁ and M₂, respectively. Each point is divided into three sectors, indicating the values of X_c for the primary (bottom sector) and the secondary star (left sector) at the time of the collision, and the value of X_c for the BSS at the zero age MS (ZAMS; top right sector). The colour-coding for X_c is reported on the left. The colour-bar ranges from 0.3 to 0.65. Values out of this range are coloured as the closest extreme on the colour scale. The BSSs’ masses are reported inside the plot, rounded to the closest multiple of 0.01.