Effect of the variation in the abundance of ⁵⁶Ni , with the other parameters fixed. All these calculations correspond to the He11 progenitor, with E_exp = 2.0 foe, a 2.15 M_⊙ compact object (then f₀ = 0.199), f₁ = 0.25, f₂ = 0.91 and f₃ = 0.991. Total M(⁵⁶Ni) given in units of solar masses is indicated in parentheses. Left: effect of variation of the inner abundance X_in. Right: same effect but related to the external abundance X_out. In the left panel, the outer abundance of ⁵⁶Ni is set to X_out = 0.01 and X_in = 0.047 in the right panel.