The active centre of the galaxy merger ESO 148-IG02.

Direct CCD-imaging, spectroscopy and Johnson UBVJHKL photometry are presented for the peculiar galaxy ESO 148 IG02. Three reasons are given for interpreting the system as a case of a late stage merging, or close encounter, between two disk galaxies. At the tip of two huge 'tidal' tails that dominate the morphology, three compact red nonstellar objects have been detected. Spectra of the central region display strong, broad (FWHM of about 600 km/s) emission lines, superimposed on an early-type stellar absorption spectrum. The level of excitation is lower than in typical Seyfert 2 galaxies but higher than in 'liners'. The emission lines exhibit blueward wings and are systematically blueshifted relative to the absorption spectrum by 320 km/s. Most of the ionization of the gas is due to hot stars, while a minor part comes from shock-heating. Further support for shocked gas comes from the abnormally strong interstellar Ca II lines. Large scale gas motions, coupled to the strongly variable gravitational field and violent cloud collisions, are probably responsible for most of the observed line broadening.