Distribution of stars in the Hertzsprung–Russell diagram for the Galactic disc sample (|Z_max|< 0.5 kpc) shown in the upper panel. The dashed black line represents the boundary condition considered to separate Main Sequence and RGB stars (Eq. C.1) neglecting extinction. Density map of the giant sample in the (X, Y) plane in the bottom panel. The solar position is denoted by a solid black circle.