The Invisible Galaxy
A new form of diffuse galaxy has been discovered inside the Coma Cluster. This place is made 99.99% of dark matter, totally invisible as it doesn’t interact with light.
The galaxy is known as Dragonfly 44 and was discovered by astronomers Pieter van Dokkum and his colleagues.
The way star systems orbit around the center of a galaxy is inexplicable with “normal” physics. To account for the velocity variations and patterns we need to add a new ingredient to the gravitational pot: dark matter.
Dragonfly 44 in particular has so few stars that were the dark matter to be taken away, the galaxy would fly apart the same way you’d go flying if the cord holding the swing to a swing set were severed.
(Image credit: NASA, JPL-CalTech and L. Jenkins)