The Impact of External Tidal Fields on the ISM of Dwarf Spheroidals
  It was found that for three dwarf spheroidal galaxies - Sculptor, Tucana, and Cetus - there is a correspondence between the distribution of associated HI gas and the projected tidal axis direction. Numerical hydrodynamical simulations confirmed the following scenario: SN Ia explosions remove most of the interstellar medium beyond the tidal radius of the dwarf galaxy, with most of the mass being in clouds moving along the principal tidal axis. 
Sergey Mashchenko and Claude Carignan