Scientists yet to understand the phenomenon.
A group of scientists has found a new galaxy which has approximately the same mass as the Milky Way and is entirely made of dark matter, reported The Washington Post.
About 99.99 percent of the galaxy named Dragonfly 44 is made up of dark matter, an unidentified type of matter comprising approximately 27% of the mass and energy in the observable universe. It barely interacts with anything.
Situated in the Coma galaxy cluster, Dragonfly 44 is about 330 million light-years from earth.
The galaxy was spotted accidentally when the scientists were studying the outskirts of galaxies.
“We planned to study the outskirts of galaxies to see what exists around them, but by accident, we saw all these little smudges,” study author Pieter van Dokkum of Yale told The Washington Post.
Surprisingly, the astronomers found the galaxy using a telescope built by a group of astronomers at Yale University and the University of Toronto using camera parts. The scientists made the telescope after realizing that telephoto lenses were better for spotting large, dim objects.
The galaxy has some normal stars of its own, comparatively much lesser than Milky Way.
The movement of the galaxy’s stars helped the scientists find out it. There is a connection between the motion of the stars and the matter.
“Motions of the stars tell you how much matter there is. They don’t care what form the matter is, they just tell you that it’s there,” Pieter van Dokkum told The Independent.
“In the Dragonfly galaxy, stars move very fast. So there was a huge discrepancy. We found many times more mass indicated by the motions of the stars than there is mass in the stars themselves,” he added.
The scientists think that there must be something that provides the gravity to hold the galaxy together. But the mass that usually provides the gravity is not there in the galaxy. So Dragonfly 44 remains as a strange galaxy.
The scientists have hardly any idea about how the galaxy was formed and how it exists.
“We have no idea how galaxies like Dragonfly 44 could have formed. The … data show that a relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue. But at the moment we’re just guessing,” co-author Professor Roberto Abraham, from the University of Toronto in Canada, said.
The study was published in Astrophysical Journal Letters.