Importance of ⁴⁰K as heat source. Upper panel: temperature evolution of the parent body model at a set of selected depths (km) considering the contributions of the full set of heat sources (red lines) for our optimised model, and a model with the same formation time and radius but with the sole contribution of ²⁶Al to heating (grey lines). Also shown for comparison are Hf-W and Pb-Pb ages and the corresponding closure temperatures for the two indicated meteorites. Lower panel: cumulated heat released, Q, up to instantt for the different contributing radioactive species.