The host galaxy and environment of the z=1.195 quasar 3C 190

We present deep imaging and spectroscopic observations of the z = 1.195 qua sar 3C 190 and its immediate environment. The quasar is surrounded by an as ymmetric, low surface brightness envelope in which there are also several g alaxies with characteristic dimensions of 3-5 kpc. Some of these form a lin ear structure some 50 kpc long in projection, offset from the quasar and al most perpendicular to the radio axis. Spectroscopy of this feature indicate s the presence of a starburst component, as well as stars a few hundred mil lion years old. Velocities of the emission-line gas associated with H II re gions in the linear feature are difficult to reconcile with any reasonable model that is also consistent with the observed morphology. One possible sc enario is an edge-on disk in an extremely massive (similar to 10(12) M-.) h alo; another is two independent chain galaxies, with the apparent alignment being fortuitous. Taking into account all of the types of extended materia l we find in the vicinity of 3C 190, we appear to be witnessing a relativel y brief phase in the development of a spheroidal galaxy, in which merging i s proceeding nearly simultaneously in a variety of different regimes. This system may be one of the clearest examples yet found for the mechanism by w hich many elliptical galaxies and bulges of early-type spirals form in the early universe.