The Milky Way has a dark twin: an international team of astronomers has discovered a massive galaxy, which consists almost entirely of dark matter. According to the researchers, 99 percent of object, called Dragonfly 44 ( “Dragonfly 44″) is exactly dark matter. The discovery of an amazing and makes astrophysicists to revise the theory of galaxy formation.
The observed galaxy is the nearest galaxy cluster called Coma. It is located about 330 million light-years from Earth. Until recently, however, researchers did not pay any attention to it until I noticed how unusual it is. Galaxy Dragonfly 44, which is of a size similar to the Milky Way, is in his “collection” is much smaller stars.
According to the scientists, originally an unusual galaxy Dragonfly 44 found specialists working with the data the telescope Dragonfly Telephoto Array, invented and built by astronomer Pieter van Dokkum (Pieter van Dokkum) from Yale University and his colleague Roberto Abraham (Roberto Abraham) from the University of Toronto. But researchers have a good look at the galaxy only by the Keck Observatory (WM Keck Observatory), situated at the peak of Mauna Kea in the US, and telescope Gemini Observatory (Gemini Observatory), the device is on the same hill.
Astronomers finally we used the Keck Observatory data, collected over six nights. Scientists have measured the speed of stars in the galaxy. Then they used the 8-meter Gemini North telescope to study the shine spherical clusters of stars around the galactic center.
The velocities of stars can determine the mass of the galaxy, the researchers note. If the light is moving faster, it has a large mass and galaxy.
“We were very surprised:. The stars were moving with a much higher rate than would have in such a dim galaxy turns out that she has a huge amount of hidden mass” – says Abraham
.
Scientists believe that such a faint galaxy at its mass is similar to the Milky Way. That is its visible part (the “normal” matter and the stars) is only one-hundredth of one percent. The remaining 99.99 percent weight falls on the dark matter – the hypothetical material that is invisible, but it probably makes more than 90 percent of the universe
The researchers note that this is not so and the news -. To detect the galaxy, most part of which is dark matter. So, ultraweak dwarf galaxies have similar compositions. But these galaxies, discovered before, were about ten thousand times less massive than the Dragonfly 44.
“We do not have any ideas about how the galaxy might form Dragonfly 44. Data Observatory show that a relatively large part of the stars is a very compact clusters, and it’s probably some kind of clue. But at the moment we can only speculate on this subject, “- says Abraham
.
One of the main goals of modern scientists – to learn more about the mysterious dark matter, so the next step of the research – to find other similar galaxies, but are closer to the Earth. They probably will be able to help set the “personality” of dark matter. By the way, some time ago the cosmic gamma-ray telescope has expanded the hunting zone for dark matter.
The study was published in the scientific journal Astrophysical Journal Letters.
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