The large face-on grand design spiral galaxy
NGC 1232 has undoubtedly interacted in complex ways with its smaller
irregular companion galaxy NGC 1232A (seen in the image on the
left) and that interaction has left an indelible mark on the larger
galaxy. The sweeping spiral arms appear to be "bent"
in areas rather than the gently curving structures seen in undisturbed
spiral galaxies. This aberration of the arms is likely due to
gravitational encounters with NGC 1232A as it orbits the larger
spiral. Radiowave studies indicate a large envelope of neutral
gas extending well beyond the optical extent of the galaxy. Rotational
velocity measurements of the galaxies huge spiral arms suggest
a large component of dark matter comprising NGC 1232. NGC1232
spans some 200,000 light years making it almost twice the size
of the Milky Way.