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E. Brinks (U. de Guanajuato, Mexico), P.--A. Duc (Inst. of Astronomy, Cambridge, England), V. Springel (Max--Planck--Institut f\"ur Astrophysik), B. Pichardo (Instituto de Astronom\'{\i}a, UNAM)
We present a multi--wavelength study of NGC~2992/3, an interacting system composed of two colliding spiral galaxies out of which emanate long stellar tails and a bridge. Both spirals show signs of nuclear activity, in particular NGC~2992, which has a Seyfert~1.9 nucleus which is obscured by a prominent dust lane. Our H\alpha map and longslit spectroscopic data indicate that the line emitting regions in NGC~2992 have a filamentary structure. Extended ELRs are observed well out of the plane of the highly inclined stellar disk. Their optical line ratios are consistent with ionizing radiation from the nucleus following a power--law spectrum whereas their kinematics indicate clear signs of outflows. HII regions are observed at the end of one of the stellar tails at the location of an object classified as a tidal dwarf galaxy. Our spectacular VLA HI map reveals a huge intergalactic rotating ring associated with NGC~2993 and a long tidal tail escaping from NGC~2992 coinciding with the optical one, with at its tip a massive clump that hosts most of the atomic gas in the system. The latter is associated with the star--forming tidal dwarf. Unlike the tail, most of the HI ring has no stellar counterpart. In the central region of NGC~2992, HI clouds detected in absorption are seen to be falling towards the nucleus, most probably fuelling the AGN.
Although NGC~2992/3 is exceptional as it gathers in a single object a number of properties sofar observed only in distinct galaxies, it has a morphology that has been fairly successfully modelled, reconstructing the history of the collision. Refinement of this model should allow us to date the onset of the various phenomena observed in this system, making it a test case for studying the effects of interactions on galaxy evolution.
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