A new major supercluster of galaxies (Earthsky.org)
By Deborah Byrd in Space | November 21, 2016
A team of astronomers from South Africa, the Netherlands, Germany, and Australia announced on November 16, 2016 the discovery of a previously unknown major concentration of galaxies in direction to the southern constellation Vela. They’ve dubbed it the Vela supercluster, and it’s one of perhaps 10 million superclusters of galaxies – vast collections of galaxies – the largest structures we know in the universe. The gravitational attraction from this newly found large mass concentration in our cosmic neighborhood might have an important effect on the motion of our Local Group of galaxies including the Milky Way, these astronomers said. It might also help to explain the direction and amplitude of our Local Group’s peculiar velocity with respect to the Cosmic Microwave Background.
Generally speaking, superclusters are vast clusters of galaxies spanning up to 200 million light-years across the sky. They’re not isolated in space but exist together with many other smaller concentrations of galaxies, together forming parts of extensive walls of galaxies surrounding large voids in what astronomers call the cosmic web.
Superclusters aren’t just big; they are also massive, meaning they have a powerful gravitational pull. They are the most massive known structures in our universe. A nearby supercluster famous for its great mass is the Shapley Supercluster, some 650 million light-years away containing two dozens of massive X-ray clusters for which thousands of galaxy velocities have been measured. It is believed to be the largest of its kind in our cosmic neighborhood.
The new Vela supercluster is slightly farther away (800 million light-years) and covers an even larger sky area than Shapley. The Vela supercluster had gone unnoticed due to its location behind the plane of the Milky Way, where dust and stars obscure background galaxies.
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more: http://earthsky.org/space/discover-major-vela-supercluster-nov-2016