Photometric diagrams M_V vs. (b − y)₀, V₀ vs. (b − y)₀ and c₁ vs. b − y. The color excess E(b − y) vs. DM is shown in the last panel. Symbols are the same as in Fig. 1: intrinsically bright stars with M_V < − 2 mag are marked by red open circles, stars intrinsically fainter than − 2 mag by black filled circles, stars from the classical Cen OB1 association by blue ×-symbols. See the electronic edition for a color version of the figure.