Collisions like the ones that produced the Antennae were much more common, and played a major role in shaping the galaxies we see around us today. They acquired their nickname from the wispy, antennae-like streams of gas caused by their merging, seen by early optical telescopes.
Many astronomers believe our own Milky Way galaxy is the product of a merger.
While galaxies may collide, the stars contained within usually do not, because stars comprise only a small fraction of the space within a galaxy. Shock wave compression of massive clouds of gas and dust can lead to the rapid birth of millions of stars. The explosion of these stars a few million years later creates thousands of supernova remnants-bubbles of multimillion degree Celsius gas enriched with oxygen, iron and other heavy elements. These expanding bubbles, collide and coalesce to form superbubbles that are five thousand light years in diameter. The X-rays from these sources are generated by gas that is heated to tens of millions of degrees Celsius as it streams from nearby companion stars onto neutron stars or into black holes.