Back in 2016, researchers claimed to have found a galaxy made almost completely of dark matter. Now that claim has fallen apart. The galaxy, Dragonfly 44 (DF44), belongs to a class of mysterious objects known as ultra-diffuse galaxies, or UDGs. Researchers have debated since the 1980s whether these vast, dim objects have a low mass, like dwarf galaxies smeared across huge reaches of space, or are heavy, Milky Way-style galaxies that seem dim for two reasons: because they have almost no stars, and because a huge fraction of their mass is dark matter found in the outer fringes of the galaxy in so-called dark matter haloes that emit no light. In a paper published in 2016 in the Astrophysical Journal Letters, scientists argued that DF44 was one of these galaxies with a big dark matter halo and few stars. They estimated its mass and found it was at least 98 per cent dark matter.
This story is from the Issue 111 edition of All About Space.
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This story is from the Issue 111 edition of All About Space.
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