Optical and IR emission of a sample of IRAS galaxies

We report on observations of 12 southem warm IRAS galaxies. Using absolute fluxes of lines in the optical region in connection with diagnostic diagrams, we have classified these galaxies in terms of the principal excitation mechanisms and have found that ali the galaxies are Seyferts. Far-infrared colours also are used to analyse these objects. Good correlations between the luminosity at 25 and 60 μm and the Hα luminosity are found. The far-infrared luminosity of Seyfert galaxies seems to depend more strongly on the number of ionizing photons than on the amount of dust