Masses at which 50% of the deuterium has been burned by 10¹⁰ years. Upper row, left: varied helium fraction. Right: varied metallicities. Lower row, left: varied maximum gas accretion rates. Right: varied deuterium abundances. The red dashed line shows the fitted functions for the hot start objects (lower line in all plots), while the fits for the cold start objects are plotted in a blue solid line (upper line in all plots). The blue diamonds show the positions of M₅₀ in the cold start runs, while the red semi-filled circles show the positions of M₅₀ for the hot start runs.