Left panel: global MDF obtained by merging the complete studied sample. Two vertical dotted red lines split the metallicity range spanned by the distribution into three regions, the two metallicity components (i) and (ii), and the metal poor tail of stars with [M/H] ≤ − 1.0 dex. Right panel: HR diagram for the complete sample. Stars located in the metal-poor tail of the MDF ([M/H] < −1.0 dex) are highlighted with a color code according to their metallicity. The two most metal-poor stars of our sample are marked by arrows.