Other pre-existent stars are likely to be destroyed as the collision continues. The two orange centers are the older surviving parts of each galaxy. Still another spectacular collision seen by HST is that just beginning between NGC2007 and NGC9941. Perhaps as many as one-third of the ancient galaxies collided during the lengthy period when galaxies were much closer, i.e., Big Bang expansion was less far along. Sometimes more than two galaxies are involved in the colliding process.
Collisions can also give rise to spiral structure.
Some globular clusters also presumably originated from interactive collision. This galaxy is only 10 million light years away and thus what we see now represents its condition at 10,000,000 years prior to today. The circular inset shows Centaurus A as seen optically through a ground-based telescope. The detailed view to the right was acquired by HST's Wide Field Camera. An elongate disc, marked by dark dust, is spread across a large white glow that is identified as an elliptical galaxy.