Properties of BGGs and single galaxies. Left panel: stellar mass log M^⋆ vs. D_n(4000) index. Middle panel: (g − r)⁰ colour index vs. absolute magnitude in r colour (colour–magnitude relation). Right panel: star formation rate logSFR vs. (g − r)⁰ colour index. The line colours correspond to groups of different luminosity and to single galaxies, as shown in the panels. The horizontal line in the left panel separates quenched and star-forming galaxies at D_n(4000) = 1.55. In the middle and right panels the horizontal line shows the division between red and blue galaxies at (g − r)⁰ = 0.7. The vertical line in the right panel shows the separation of quenched and star-forming galaxies at logSFR = −0.5.