Half of the Milky Way comes from other galaxies | Science News

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Half of the Milky Way comes from other galaxies

Simulations suggest that galactic winds blew the material in from elsewhere

9:00pm, July 26, 2017
galaxies M81 and M82

STEALING GAS  The galaxies M81 (left) and M82 (right) may be exchanging gas. Supernova explosions in M82 would toss out gas that could be pulled toward M81, helping it bulk up.

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Galaxies may grow by swiping gas from their neighbors.

New simulations suggest that nearly half the matter in the Milky Way may have been siphoned from the gas of other galaxies. That gas provides the raw material that galaxies use to build their bulk. The finding, scheduled to appear in the Monthly Notices of the Royal Astronomical Society, reveals a new, unexpected way for galaxies to acquire matter and could give clues to how they evolve.

“These simulations show a huge amount of interaction among galaxies, a huge dance that’s going on,” says astronomer Romeel Davé of the University of Edinburgh. That dance, and the subsequent exchange of atoms, could be what establishes a galaxy’s character — whether it’s small or big,

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