JETS AND THE EMISSION-LINE SPIRAL STRUCTURE IN IRAS-04210+0400

We examine models in which jets are responsible for the formation of t he emission-line spiral structure in IRAS 04210 + 0400. The kiloparsec -scale radio lobes in this active galaxy appear to be related to its e xtended emission-line spiral structure. The radio structure consists m ainly of extended symmetrically bent, FR I-type lobes, which follow th e emission-line spiral structure at their inner edge. In the central r egion of the galaxy a double radio source is observed with a separatio n of approximately 1 arcsec between its components, which are extremel y well aligned with the hotspot from which the southern lobe expands o utwards. Hill et al. suggested a model for the emission-line spiral st ructure invoking compressed interstellar matter, which is dragged away from the original jet path by the rotating ambient medium. From consi deration of the propagation speed of the jets and the transverse ram p ressure exerted by the rotating environment, we exclude this scenario as a possible origin of the spiral structure. We favour a model in whi ch the jets themselves are bent by the rotating interstellar medium an d possibly follow the emission-line spiral arms. We present fits of th e model to the observed optical spiral structure. High-sensitivity rad io observations will be required to decide on the nature of the peculi ar spiral structure in IRAS 04210 + 0400.