Tidally induced bars in gas-rich dwarf galaxies orbiting the Milky Way
  Bars in galaxies may form not only through instability, but also as a result
of an interaction with another galaxy. In particular, they may appear in disky
dwarf galaxies interacting with Milky Way-like galaxies. Here we report the
results of N-body/SPH simulations of such dwarfs orbiting in the static
potential of a larger galaxy. We used several models of the dwarf galaxy, all
of the same mass, but covering a large range of gas fractions: 0, 30 and 70%.
We also tested the impact of subgrid star formation processes. In all cases
bars of similar length formed in the stellar disk of the dwarfs at the first
pericenter passage. However, unexpectedly, the gaseous component remained
approximately axisymmetric and unaffected by the bar potential. The bar
properties did not change significantly between two consecutive pericenters.
The impact of the later encounters with the host depends strongly on the exact
orientation of the bar at the pericenter. When the bar is spun up by the tidal
force torque, it is also shortened. Conversely, if it is slowed down, it gets
longer. In the models with a low gas fraction the bars were more pronounced and
survived until the end of the simulations, while in the dwarfs with a high gas
fraction the bars were destroyed after the second or third pericenter passage.
In terms of the ratio of the corotation radius to the bar length, the bars are
slow, and remain so independently of the encounters with the host.
