Massive 'ghost' galaxy made of 99.99% dark matter discovered by astronomers

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However, only one hundredth of one per cent of that is in the form of stars and "normal" matter.

A team of North American astrophysicists has found a very large, very dim blob and it challenges what we think about dark matter, a.k.a. the stuff that makes up most of the universe. But those galaxies were roughly 10,000 times less massive than Dragonfly 44. It measures about 60,000 light years across, a little over half the width of our own galaxy, but it contains less than 1 percent of the stars.

The galaxy was identified last year in the Coma galaxy cluster (pictured), about 330 million light years away. "Dragonfly 44 changes that notion: it seems there is a huge variety".

The team then used the Gemini Multi-Object Spectrometer (GMOS) on the eight-metre Gemini North telescope to reveal a halo of spherical clusters of stars around the galaxy's core, similar to the halo that surrounds our Milky Way galaxy. On the right is a close-up view of the same image.

The dark galaxy known as Dragonfly 44 is about 330 million light years away, and weighs about as much as our Milky Way galaxy. Dragonfly 44's stars are behaving as if they are in a galaxy the size of the Milky Way, except they are much more diffuse.

'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. "That's just something we never knew could happen".

Dragonfly 44 is very faint for its mass and consists nearly entirely of dark matter. There are too few of them, and they are spread too thin. Either that, or they're unstable - and the violent Coma cluster is now ripping them to shreds. So the Keck team made a decision to take a closer look at Dragonfly 44. They looked at not just the brightness of the stars, but how fast they were spinning.

'In the Dragonfly galaxy, stars move very fast.

The two Keck Telescopes on top of Mauna Kea in Hawaii.

Ghost Galaxy
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Professor Pieter van Dokkum, of Yale University, said it looked unusual because the stars were moving at a fast rate within the galaxy. In a typical galaxy, these signals are drowned out by the noise of stars and other matter around them.

"If it's a very big or very large galaxy, you can brush it off and say, oh, that must be a rare thing", he said, "but most of the stars in the universe live in galaxies this size".

This is a common technique to calculate the amount of dark matter in a galaxy. They spent six nights imaging the galaxy to be sure of its mass.

A massive galaxy consisting nearly entirely of dark matter has been discovered, using the world's most powerful telescopes.

They realised the galaxy had to have more than meets the eye; it has so few stars that it quickly would be ripped apart unless something was holding it together - dark matter. Theoretically, it makes up 85 percent of all matter in existence.

The instruments which are used to find normal matter like hot gas, stars and planets are unable to find dark matter.

A mysterious "ghost" galaxy that has been overlooked by astrologers for decades because it is so hard to see has finally been discovered.

"We have no idea how galaxies like Dragonfly 44 could have formed", said Abraham.

Using the world's most powerful telescopes, an worldwide team of astronomers has found a massive galaxy that consists nearly entirely of dark matter.