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Massive galaxy discovered made almost entirely of dark matter

26 August 2016 Astronomy Now

An international team of astronomers has discovered a massive galaxy that consists of 99.99 percent dark matter. Even though it is relatively nearby, astronomers had missed the galaxy, named Dragonfly 44, for decades because it is very dim. The galaxy lies about 300 million light-years away in the constellation Coma.

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The dark matter conspiracy

3 May 2015 Astronomy Now

A new study finds that elliptical galaxies maintain a remarkably constant circular speed out to large distances from their centres, in the same way that spiral galaxies do. In these very different types of galaxies, stars and dark matter somehow conspire to redistribute themselves to produce this effect, or does modified Newtonian dynamics offer an explanation?