The fluffiest galaxies ever seen in the universe have been discovered by astronomers. This class of diffuse collections of stars can be up to 60,000 light years in diameter - almost as large as our own Milky Way - but contain just 1 percent as many stellar bodies.
These newly described ultra-diffuse galaxies (UDG's) sit roughly 300 million light years from the Earth. Measurement of the distance allowed astronomers to determine the sparse population of these collections of stars.
"We are beginning to form some ideas about how they were born and it's remarkable they have survived at all. They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter 'shields' that are protecting them from this intergalactic assault," said Pieter van Dokkum from Yale University.
The W. M. Keck Observatory was utilized to study these galaxies using the world's largest telescope, as well as amateur-sized telephoto lenses just 5.6 inches in diameter. The large telescope was used to measure the composition of the galaxies, as well as the distance to the stellar families. This data was compiled with digital images of the bodies taken of the bodies.
The Coma Cluster, a region of space were the fluffy galaxies were located, is filled with a myriad of galaxies, drawn together by gravity, as well as dark matter. These areas can cause havoc on the collections of stars, so the appearance of fluffy galaxies there remains a mystery.
"Because these newly discovered galaxies are found in a very active, violent part of space, scientists think that the systems may have invisible dark matter 'shields' that help them survive. The discovery adds to what we know about the diversity of galaxies, which already range from giant ellipticals to ultracompact dwarfs," Science magazine reported.
Astronomers want to know how these UDG's formed. One possibility is they were once normal galaxies which were ripped apart by the enormous forces in that region of space. They may also be failed galaxies, ones which never completed the process of forming, or the objects could be comprised of pieces of other galaxies that were torn off their parent bodies.
Any alien civilization living in these fluffy galaxies would see few stars over their planet, and there would be no band of light stretching across the night sky like we see from the Milky Way.
Discovery of the fluffiest galaxies in the Universe was detailed in the Astrophysical Journal Letters.
