The Milky Way will probably devour all the tiny galaxies that surround it

Ars Technica » Scientific Method 2023-12-07

a colorful, roughly circular cloud with stars against a dark background.

Enlarge / An infrared image of one of the Milky Way's satellite galaxies. (credit: NASA/JPL-Caltech/STScI)

We are not alone—at least as a galaxy. About 50 dwarf galaxies surround the Milky Way. But when its intense gravity inevitably draws them to venture too close, they will probably be annihilated. It’s happened before.

Though scientists used to think that all those dwarf galaxies orbiting the Milky Way were going to stick around for tens of billions of years, that might not be the case. “Most dwarf galaxies are star systems that arrived late in the Milky Way… in sharp contrast with a long-term satellite hypothesis,” an international team of researchers said in a study recently published in Monthly Notices of the Royal Astronomical Society.

Based on data from the European Space Agency’s Gaia mission, this study has found that many dwarf galaxies that were orbiting the Milky Way only a few billion years ago have ended up destroyed after being pulled in by our much more massive galaxy. It is possible dark matter has something to do with this.

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