Dragonfly Galaxies

The existence of the UDG, Ultra Diffuse Galaxies was confirmed. They are scattered clusters of stars that must accommodate proportionally much dark matter in order to be together. “If the Milky Way was a sea, then these galaxies would be the clouds,” says Pieter van Dokkum of Yale University.
An international team of researchers, led by Pieter van Dokkum of Yale University, has used large telescopes the Keck Observatory in Hawaii to confirm the existence of a new class of galaxies called Ultra Diffuse Galaxies (UDGs), whose members have The distribution of stars sparser known.
These “balls” cosmic extensions have almost equal to that of the Milky Way, about 60,000 light years, but possessing only one percent of the stars than galaxies like ours. The results of this research were recently published in the journal Astrophysical Journal Letters.



“If the Milky Way was a sea of stars, then these newly discovered galaxies would clouds,” said van Dokkum. “We are beginning to form an idea of how they were born, and it is truly remarkable that have managed to survive it all. They are, in fact, in a dense and violent region of space, packed with dark matter and galaxies whizzing all around; therefore we believe that should be cloaked in an invisible shield of dark matter that protects them from this onslaught Intergalactic “.
The 47 new “vaporous” galaxies were discovered by van Dokkum and colleagues, last November in the Coma cluster – a grouping of thousands of galaxies, large and small – with a very special telescope, the Dragonfly Telephoto Array, specially designed to detect weak and poorly defined lumps of stars.
The discovery did stay stunned the researchers, but they had to make further checks, in particular to determine the exact distance. A decisive feature that has now been achieved through the Lris spectrograph mounted on one of the twin Keck telescopes.


Credit: P. van Dokkum, R. Abraham, J. Brodie

In the delicate iridescence spectral new galaxies Dragonfly (Dragonfly), van Dokkum and colleagues have read that these blobs are very large and very distant, about 300 million light years. You can therefore speak of a new class of galaxies “ultra-spread”.
“The inhabitants of a planet in a galaxy ultra-widespread would not see any bright band in the sky, as we see the Milky Way. Would have no way to say that they live in a galaxy, and their night sky would be much emptier of stars,” says team member Aaron Romanowsky of San Jose State University.
“Our thin objects are in addition to the wide variety of types of previously known galaxies, from giant elliptical, the size that cloud the Milky Way, the ultra-compact dwarfs”, adds Jean Brodie of the University of California.


Credit: P. van Dokkum, R. Abraham, J. Brodie

According to the researchers, the next major step in the understanding of galaxies ultra-popular is to define exactly how much dark matter they contain.
“The big challenge now is to understand where they come from these mysterious objects,” he says in conclusion Roberto Abraham of the University of Toronto, listing the questions that they face as a result of new discovery. “These galaxies” failed “, which started off well and then were run out of gas? Or galaxies were “normal” that have been so harass within the cluster Coma by reason to be emptied? Or are pieces of larger galaxies, ripped away and then lost in space? ».

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