In the middle of XX century, large telescopes revealed that approximately 10% of galaxies are rather unusual in their appearance. These galaxies did not fit into Hubble's classification.
Such galaxies are sometimes surrounded by a radiating halo, or are connected by a bar. In some cases, long "tails" stretch for hundreds of thousands of light-years from the central locations of these galaxies. Complex patterns of inner motion of cosmic gases are apparent in some of these systems.
When galaxies on the move closely approach each other, they may experience strong remote gravitational interaction even without coming into direct contact. In the cases of mutual penetration, galaxies may merge for several hundred million years. A famous pair of galaxies - the Antenna and Stefan's Quintet - provides us with a good example of such interacting systems.
Our Galaxy is gradually entrapping a dwarf galaxy that is currently located at the distance of only 60 thousand light years away. Stars of this dwarf galaxy will become stars of our Galaxy after one hundred million years. Milky Way will completely absorb the substance of the Magellan Clouds during the next 10 billion years.
Star "cannibalism" is common in the life of galaxies. Absorption processes of galaxies are not accompanied by catastrophic collisions of stars, since cosmic distances are too great in comparison to sizes of the stars. However, star formation processes may become more prolific, since massive clouds of gas are forming, and their velocities are increasing under the impact of gravity.
This dynamic model illustrates the phenomenon of two merging galaxies. Press "Run" button to observe how the galaxies rotate as they approach each other. Ultimately, the galaxies will merge, and their stars will form a unified galaxy, as it has happened with Centaurus A galaxy. The model will stop when two billion virtual years elapse.
"Stop" and "Reset" buttons bring the model to a halt and return it to its initial state, respectively.