Galaxy colour, morphology and environment in the Sloan Digital Sky Survey

We use the Fourth Data Release of the Sloan Digital Sky Survey to investigate the relation between galaxy rest-frame u-r colour, morphology, as described by the concentration and Sérsic indices, and environmental density, for a sample of 79 553 galaxies at z¿ 0.1. We split the samples according to density and luminosity, and recover the expected bimodal distribution in the colour-morphology plane, shown especially clearly by this subsampling