Milky Way Settles Into Its New Home, The Laniakea Supercluster

The Milky Way galaxy is an outlier in an enormous, newly designated supercluster of galaxies dubbed Laniakea. The vast assemblage spans some 500 million light years across and contains the mass of one quadrillion suns. The Local Supercluster, centered in Virgo, is only a small part of the much larger Laniakea. The looping lines represent galaxy flows toward large concentrations of galaxies within the supercluster. Credit: SDvision interactive visualization software by DP at CEA/Saclay, France (additions by B. King)

The name fits so well – Laniakea. It means ‘immense heaven’ in Hawaiian, and now it’s home. In the biggest sense of ‘big picture’ you can imagine.

Astronomers using the National Science Foundation’s Green Bank Telescope (GBT), among other telescopes, have determined that our own Milky Way galaxy is part of a newly identified titanic supercluster of galaxies they nicknamed  Laniakea (Lah-nee-ah-KAY-uh).

The Hercules Cluster in the constellation Hercules is a good example of a rich galaxy cluster. It contains about 200 galaxies and is located 500 million light years away. The cluster is a member of the Hercules Supercluster. Credit: Jim Misti

The Milky Way’s always been in one gang or another. It’s a member in good standing of the Local Group, a gravitationally bound small cluster of some 54 neighborhood galaxies. It in turn, along with dozens of other clusters, are drawn by gravity to the granddaddy Virgo Cluster, which contains some 2000 galaxies 53 million light years away.

All these clusters are interconnected, linked into a web through mutual gravitational attraction. Taken together, they’re known as the Local Supercluster, and superclusters are the single biggest structures in the universe. Our Local Supercluster contains at least 100 different galaxy groups and stretches across 110 million light years.

Another view of the Laniakea Supercluster. The outer surface (blue) shows the region dominated by the supercluster’s gravity. The streamlines shown in black trace the paths along which galaxies flow as they are pulled closer inside the supercluster. The historical Local Supercluster in shown in green and the Great Attractor region in orange. Credit: SDvision interactive visualization software by DP at CEA/Saclay, France

Up till now we thought it was the biggest structure of which the Milky Way was a part. Not anymore.

R. Brent Tully from the University of Hawaii’s Institute for Astrophysics and his team studied the motions of galaxies in the Local Supercluster and discovered that we live in a MUCH bigger house than we ever thought.

By using the GBT and other radio telescopes to map the velocities of galaxies throughout our local universe, the team was able to define the region of space where each supercluster dominates. They found that superclusters are involved in a tug of war for galaxies – many are pulled into the supercluster while those near the edge are up for grabs.

By studying these streaming motions, Tully and team discovered that our historical supercluster home was itself part of a much larger supercluster I’m almost tempted to call the Local Superdupercluster (but I won’t). Doubtless the more poetic Laniakea was picked because of Tully’s Hawaii connections.

Meet Laniakea, the Milky Way’s home supercluster

“We have finally established the contours that define the supercluster of galaxies we can call home,” said Tully. He compared it to realizing for the first time that your hometown belongs to a much larger country bordering other nations (superclusters).

Not only do large galaxy clusters dominate the new landscape, but an enigmatic mass of distant galaxies called the Great Attractor is also a bona fide member.

It’s cool being part of something even bigger than we’d ever imagined. I just had a gut feeling the Milky Way needed more space.

6 Responses

    1. astrobob

      Thanks Andrew. I really like the diagram showing how relatively small the Virgo (Local) Supercluster is compared to the Laniakea.

  1. Steve Behram

    What a beautiful rendition of the filamentous infrastructure of galaxies in our universe. Interestingly, the galactic motions within this supercluster lead to an inward motion after correction of cosmic expansion, but eventually, the cosmic expansion will win out and the filament will eventually be dispersed in the cosmic wind. Thank you for the interesting post and the hypnotic images of Laniakea, Bob.

    1. astrobob

      That’s tricky, but if we take the map at face value with the Milky Way off to one side near Virgo, it appears that Antlia-Centaurus is the direction of the center however that doesn’t appear to be the center of mass of the cluster.

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