Distribution of stars in the [α/Fe] vs. [Fe/H] plane. Chemical properties are taken from APOKASC. The dashed lines show the limits used to separate the three disc populations: hαmp, hαmr thick discs, and thin discs (top and middle panels). Middle panel: excludes the thin disc stars to focus on the thick disc stellar populations. Bottom panel: the sample is separated into three populations: Thin disc, hαmr, and hαmp thick-disc populations are represented with orange, purple, and blue dots, respectively.