Diversity of light curves for different ⁵⁶Ni distributions and density profiles. Panel a: light curves are shown for our EXP_Ni0.6_KE1.10 model with different scaling parameters and ⁵⁶Ni distributions calculated from the Eq. (5). Symbols show different bands of observations, which have been arbitrarily offset. The legend for symbols in panels a and b, is given in panel b. Models with smaller scale parameters (i.e. more extended ⁵⁶Ni distributions) show brighter light curves at early times. Panel b: light curves calculated with different density profiles are shown for the case of models with 0.6 M_⊙ of ⁵⁶Ni and a scale parameter of s = 9.7. Colours in panel b are as in panel c. Panel c: density profiles for light curves shown in panel b. All models have a maximum velocity of 30 000 km s⁻¹.