A study of two dwarf irregular galaxies with asymmetrical star formation
  distributions
  Two dwarf irregular galaxies DDO 187 and NGC 3738 exhibit a striking pattern
of star formation: intense star formation is taking place in a large region
occupying roughly half of the inner part of the optical galaxy. We use data on
the HI distribution and kinematics and stellar images and colors to examine the
properties of the environment in the high star formation rate (HSF) halves of
the galaxies in comparison with the low star formation rate (LSF) halves. We
find that the pressure and gas density are higher on the HSF sides by 30-70%.
In addition we find in both galaxies that the HI velocity fields exhibit
significant deviations from ordered rotation and there are large regions of
high velocity dispersion and multiple velocity components in the gas beyond the
inner regions of the galaxies. The conditions in the HSF regions are likely the
result of large-scale external processes affecting the internal environment of
the galaxies and enabling the current star formation there.
