Evolutionary tracks for all WD models. Left panel: HR diagram for all WD models. All observed D⁶ stars are plotted as black points. The dashed red lines represent the lines of constant radii. The colour bar shows the log(age) of the star. The arrows mark the points when the model is 10⁴ years old. Right panel: Kiel diagram for the same model. The high uncertainty in J0546 comes from combining the minimum and maximum values from Werner et al. (2024) and El-Badry et al. (2023), which have different ways of measuring the radius that lead to inconsistent results.