NGC 6240, also known as the Starfish Galaxy, is a fascinating example of a galaxy merger. Located about 400 million light-years away in the constellation Ophiuchus, NGC 6240 is the result of a collision between three smaller galaxies. This cosmic event has created a single, larger galaxy with a highly disturbed structure, including faint extensions and loops.
One of the most intriguing features of NGC 6240 is its double nuclei, which are actually two supermassive black holes spiraling closer and closer to one another. These black holes are expected to merge into a single, even more massive black hole over the course of millions of years. The galaxy is also an ultraluminous infrared galaxy (ULIRG), meaning it is extremely bright in the infrared spectrum due to intense star formation and active galactic nuclei.
The merging process has triggered frantic bursts of star formation, creating distorted tidal tails of stars, gas, and dust. This dramatic scene has been captured in stunning images by the Hubble Space Telescope and other observatories.
You can find more information on Wikipedia and APOD.