Metallicities and masses of our stars alongside with the density distribution of APOKASC-3 for RGB stars (upper panel) and RC stars (lower panel). The α-rich stars are plotted in the left-hand panels, and the α-poor stars are plotted in the right-hand panels. The chemical separation uses Eq. (2). Contours indicate the percentages 10, 20, 30%, and so on of the APOKASC-3 distributions. The outer contour corresponds to 90% of the stars being inside the distribution.