Lower panel: luminosity functions for hydrogen-atmosphere white dwarfs with masses between 0.9 and 1.1 M_⊙. Observational data from Tremblay et al. (2019) are shown in red and their population synthesis is represented by the dotted curve. Results from our own simulations are shown as dashed and solid lines (with and without an attempt to simulate the effect of ²²Ne phase separation, respectively). The normalization is arbitrary, and the Gaia G magnitude limit from Gentile Fusillo et al. (2019) is used. Upper panel: evolution of the fraction of the core that is crystallized for the 1.1, 1.0, and 0.9 M_⊙ sequences.