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Shredded Cluster

August 17, 2016

You don’t want to mess with the Milky Way. Our home galaxy is especially big and heavy, so its gravity can tear apart star clusters and even entire galaxies. And astronomers recently discovered one such victim: a globular star cluster that is no more.

A globular cluster contains hundreds of thousands of stars packed into a ball that’s only a few dozen light-years across. The Milky Way has more than 150 such clusters.

The constellation Draco, the dragon, features a globular that the Milky Way has torn to shreds. Astronomers discovered it after noticing a streamer of stars that were all racing through space at the same speed. The stars also share the same chemistry, and they’re all more than twice as old as the Sun — a trait of the Milky Way’s globular clusters.

Known as LAMOST-1, the shredded cluster is only 8600 light-years from Earth. That’s not much farther than the nearest surviving globular.

Although the cluster no longer exists, its stars keep shining. Today, they orbit the center of the Milky Way individually instead of as a group. At their closest point, they pass just 2500 light-years from the galactic center; at their farthest, they’re 26,000 light-years out — nearly the same distance as we are.

Once held close together by their mutual gravitational pull, the stars of this dead cluster now circle through the galaxy on their own — stripped from their stellar home by the gravity of the Milky Way.


Script by Ken Croswell, Copyright 2016

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