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Under an especially dark night sky, away from city lights, you might see a few thousand stars. All of them belong to our home galaxy, the Milky Way. But not all of them were born in the Milky Way. It’s likely that some of them were born elsewhere, but the Milky Way swallowed their home galaxies, making the stars its own.
In fact, astronomers recently announced the discovery of 11 streamers of stars in the Milky Way that are remnants of other galaxies. The streams were created when smaller galaxies flew too close to the Milky Way and were captured by its powerful gravity. The Milky Way ripped the galaxies apart, turning the agglomerations of stars into streamers that can span thousands of light-years.
Incorporating the stars of other galaxies has helped the Milky Way grow to giant proportions. Astronomers had already discovered the remains of a couple of dozen small galaxies ingested by the Milky Way. Several other small galaxies are so close to the Milky Way that they’re likely to be pulled in as well.
The new streamers were discovered by the Dark Energy Survey. It uses a giant camera to photograph the entire sky. The goal is to help astronomers understand the cause of dark energy, which is causing the universe to expand faster as it ages. But the survey’s images allow astronomers to study a lot more than just dark energy. In this case, they revealed the new streamers of stars — the remains of small galaxies that are now part of our own.
Script by Damond Benningfield