#dark galaxies

[astroquizzical]

Could Dark Matter Ever Form A Star?

"Does dark matter have mass? Could dark matter ever form a star?"

Having mass is the one thing that’s really certain about dark matter. Dark matter's existence was discovered by measurements that meant that there had to be some extra, invisible, material, which was contributing mass to the galaxies we were looking at. What kind of material it is exactly...

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Thousands Of Galaxies Are In The Dark

Thousands Of Galaxies Are In The Dark

Thousands Of Galaxies Are In The Dark By Judith E Braffman-Miller

Strange objects lurk in our weird Universe, hiding secretively in bewitching darkness, making themselves difficult to see. Dark galaxiesare just such mysterious objects, that can hide themselves very well in our Universe’s most secretive places because they have no, or very few, stars to shed light on their shadowy, ghostly…

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[universetoday]

Dwarf Dark Matter Galaxy Hides In Einstein Ring

Dwarf Dark Matter Galaxy Hides In Einstein Ring

Everybody knows that galaxies are enormous collections of stars. A single galaxy can contain hundreds of billions of them. But there is a type of galaxy that has no stars. That’s right: zero stars.

These galaxies are called Dark Galaxies, or Dark Matter Galaxies. And rather than consisting of stars, they consist mostly of Dark Matter. Theory predicts that there should be many of these Dwarf Dark…

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[thenewenlightenmentage]

Outer Edges of Milky Way Orbited by Invisible Galaxies

The outer edges of the Milky Way's appear to be orbited by innumerable invisible galaxies, one of which appears to be crashing into our own. In 2005 astronomers discovered the first evidence of mysterious dark galaxies with no starlight - VirgoHI 21 - a cloud of hydrogen in the Virgo Cluster 50 million light-years from the Earth found to be colliding with our galaxy. VirgoHI 21 revealed its existence from radio waves from neutral hydrogen coming from a rotating cloud containing enough hydrogen gas to spawn 100 million stars like the sun and fill a small galaxy.

The rotation of VirgoHI21 is far too fast to be consistent with the gravity of the detected hydrogen. Rather, it implies the presence of a dark matter halo with tens of billions of solar masses. Given the very small number of stars detected, this implies a mass-to-light ratio of about 500, far greater than that of a normal galaxy (which would be around 50). The large gravity of the dark matter halo in this interpretation explains the perturbed nature of the nearby spiral galaxy NGC 4254 and the bridge of neutral hydrogen extending between the two entities.

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[ookii]

Astronomers in Chile have observed what appears to be evidence of the existence of dark galaxies, the European Southern Observatory (ESO) announced on Wednesday.

The European Southern Observatory's Very Large Telescope in Chile's Atacama Desert and (right) the region surrounding the quasar HE0109-3518 Photo: EPA

Dark galaxies are small, gas-rich galaxies from the early universe that are believed to be the building blocks of today's bright, star-filled galaxies, said the ESO, an intergovernmental organisation supported by 15 countries.

"For the first time, dark galaxies – an early phase of galaxy formation, predicted by theory but unobserved until now – may have been spotted," the ESO said in a statement.

"Using ESO's Very Large Telescope, an international team thinks they have detected these elusive objects by observing them glowing as they are illuminated by a quasar," it said.

The ESO is the most advanced astronomical observatory in the world, and operates three sites in Chile.

The Very Large Telescope (VLT) array – a cluster of four telescopes that can view objects four billion times fainter than objects visible to the naked eye – is housed at the ESO's Paranal site in Chile's Atacama Desert.