Evolutionary tracks for all WD models without any helium removed. [left panel] HR diagram for grid 1 models. All reported D⁶ stars are plotted as black points. Red lines represent lines of constant radii. The colour bar shows the log(age) of the star. [right panel] Kiel diagram for the same model. The high uncertainty in J3546 comes from combining the minimum and maximum values from Werner et al. (2024) and El-Badry et al. (2023). The big loop of 0.50 M_⊙ and the smaller loop of 0.64 M_⊙ models is due to unstable helium burning.