The Development of Gas/Star Offsets in Tidal Tails

We present models of interacting galaxies in order to study the developmentof spatial offsets between the gaseous and stellar components in tidal tails.Observationally, such offsets are observed to exist over large scales (e.g.,NGC 3690; Hibbard et al. 2000), suggesting an interaction between the tidal gasand some (unseen) hot ISM. Instead, our models show these offsets are a naturalconsequence of the radially extended HI spatial distribution in disk galaxies,coupled with internal dissipation in the gaseous component driven by theinteraction. This mechanism is most effective in systems involved in veryprograde interactions, and explains the observed gas/star offsets ininteracting galaxies without invoking interactions with a hot ISM, starburstionization, or dust obscuration within the tails.