Astronomers have found a massive galaxy about the size of the Milky Way made almost entirely of dark matter. The galaxy, Dragonfly 44, is located in the nearby Coma constellation.
The team was able to get a good look at Dragonfly 44 using the W M Keck Observatory and the Gemini North telescope in Hawaii.
Using observations taken over six nights, astronomers measured the velocities of stars in the galaxy.
They unveiled a halo of spherical clusters of stars around the galaxy’s core, similar to the halo that surrounds our Milky Way galaxy.
Star velocities are an indication of the galaxy’s mass. The faster the stars move, the more mass its galaxy will have.
Dragonfly 44’s mass is estimated to be one trillion times the mass of the Sun, which is similar to the mass of the Milky Way.
However, only one-hundredth of one per cent of that is in the form of stars and “normal” matter. The other 99.99 per cent is in the form of dark matter – a hypothesised material that remains unseen but may make up more than 90 per cent of the universe.