Hickson 40 resides at a distance of 300 million light years[1] and is so dense[2] that it could even exist within a region close to the diameter of the Milky Way's galactic disk.

Researchers have observed Hickson 40 in many wavelengths, including visible light, radio, infrared, and X-ray.

[4] Majority of the galaxies within the cluster have a dense radio source in the cores, which could be proof for the existence of supermassive black holes.

X-ray surveys have revealed that the galaxies are pushing closer together because of the amount of hot gas present.

[5] Hickson 40 is one of the most compact galaxy clusters ever observed, making it a valuable research point NASA.