Colour-magnitude diagram (g − r)₀ vs. M_r for galaxies in SCl A2142. Filled circles correspond to galaxies in rich groups, and empty circles show galaxies in poor groups (including single galaxies). The red circles correspond to the galaxies with old stellar populations (D_n(4000)≥1.55) and the blue circles to the galaxies having young stellar populations with D_n(4000)< 1.55. The green triangles show recently quenched galaxies with D_n(4000)≤1.55 and star formation rate logSFR < −0.5. The red triangles indicate red, high SFR galaxies defined as g − r ≥ 0.7, and logSFR ≥ −0.5. Orange stars represent AGNs. The dashed line shows the completeness limit M_r = −19.6 + 5log₁₀ h.