1999MNRAS.308..364C

We present both observations and modelling of the atomic hydrogen in the closely interacting galaxies NGC 3395 and 3396. The observations were made with the VLA in both C- and D-arrays. We detect a large `tail' of Hi extending to a projected distance of 63kpc (10arcmin) south-west of the pair, as well as two smaller galaxies, IC 2604, 14arcmin to the south-west, and IC 2608, 14arcmin to the south-east. However, these galaxies appear to have had at most a minor influence on the dynamics of NGC 3395/6. By means of N-body simulation we show that the tail is gas that has been stripped from NGC 3395 during a prograde encounter with NGC 3396, and that the pair has had one previous close approach. It is shown that the galaxies are within 5x10⁷yr of their second perigalactic passage. Comparison of the time-scales for starburst activity with those from the simulations shows that the current starbursts are a result of the current close approach and not the first one. The interaction between NGC 3395 and 3396 has flattened the rotation curve of NGC 3396 owing to the parameters of the interaction. This naturally explains the more nucleated radio continuum structure observed in this galaxy, as significant infall and a subsequent central starburst would be expected in this scenario. The velocity structure and line profiles of the Hi are best explained if both cloud-cloud collisions between the two gas discs and tidal forces have been important.