An international team of astronomers headed by Dr R. Brent Tully of the University of Hawaii has determined that our Milky Way Galaxy lives in a newly discovered supercluster of galaxies, dubbed Laniakea.
A slice of the Laniakea Supercluster in the supergalactic equatorial plane. Our Milky Way Galaxy is located at the black dot at the origin of the supergalactic coordinates system. The colors represent density within this slice, with red for high densities and blue for voids – areas with relatively little matter; individual galaxies are shown as white dots; velocity flow streams within the region gravitationally dominated by Laniakea are shown in white, while dark blue flow lines are away from the Laniakea local basin of attraction; the orange contour encloses the outer limits of these streams, a diameter of about 522 million light-years. Image credit: DP / CEA / Saclay, France.
Superclusters are among the largest structures in the known Universe.
They are made up of groups, like our own Local Group, that contain dozens of galaxies, and massive clusters that contain hundreds of galaxies, all interconnected in a web of filaments.
Though these structures are interconnected, they have poorly defined boundaries.
To better refine cosmic mapmaking, Dr Tully and his colleagues proposed a novel way to evaluate these large-scale galaxy structures by examining their impact on the motions of galaxies.
By using radio telescopes to map the velocities of galaxies throughout our local Universe, the astronomers were able to define the region of space where each supercluster dominates.
According to the team, our Galaxy resides in the outskirts of one such supercluster, the Laniakea (‘immense heaven’ in Hawaiian). The name honors Polynesian navigators who used knowledge of the heavens to voyage across the immensity of the Pacific Ocean.
“We have finally established the contours that define the supercluster of galaxies we can call home,” said Dr Tully, who is the first author of a paper publuished in the journal Nature.
This galactic supercluster is 522 million light-years in diameter and contains the mass of one hundred million billion Suns spread across 100,000 galaxies.
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R. Brent Tully et al. 2014. The Laniakea supercluster of galaxies. Nature 513, 71–73; doi: 10.1038/nature13674
