Nuclear heating rates of the explored parameter space, colours label Y_e-values. Overlaid are bolometric lu- minosities computed following the description in Kasliwal et al. (2017) using updated photometry from https://kilonova.space (yellow circles). We show the total nuclear heating rate (luminosities divided by an ejecta mass of 1.5 × 10⁻² M_⊙). Also shown is the heating rate of a wind with Y_e = 0.5 that produces a substantial amount of nickel, see last panel in Fig. 2. The close agreement with Y_e ≲ 0.3 strongly suggests the presence of substantial amounts of r-process matter.