α-element abundance ([α/Fe]) as a function of global metallicity ([M/H]) of the main sequence stars (log g > 4.0 dex) and good quality flags (the first 13 digits in flags_gspspec equal to zero). All parameters were derived by GSP-Spec (Recio-Blanco et al. 2023c). Colour indices show the values of the colour C1M395−C1M410 (top panel), which is changing due to the α abundance and C1M326−C1M410 (bottom panel), which depends more on the global metallicity. Contours indicate density dropping by factors of 5.