Thursday, December 9

A cannibal universe: the Magellanic Cloud has swallowed up other galaxies on its way to collide with the Milky Way

Our galaxy has absorbed with other galaxies, and those that are on the way to being absorbed have also absorbed more galaxies. It is the conclusion reached a new study from the University of Bologna, which suggests that the Magellanic Cloud that surrounds our Milky Way “has eaten” a galaxy on its way.

The Magellanic Cloud is a group of stars divided into a large and a small Cloud, which move (apparently by interaction with dark matter) towards our galaxy to end up colliding with it in 2 billion years.

The big one eats the little one

This is a more common process than we imagined, because that group of stars that is going to be “swallowed” by the Via Lactica would have done the same with other smaller galaxies. The study reinforces the theory of hierarchical formation: Large galaxies are large because they have absorbed smaller galaxies.

In fact, the Magellanic Cloud would still be in full swing: several small, very diffuse and small galaxies have been detected around it. The big one eats the little one, on all scales. And best of all, we can determine the age of each galaxy by analyzing the metallicity (or proportion of heavy elements) of its components.

Thus we can build a “history” of absorptions from the remnants of ancient galaxies orbiting larger galaxies, which usually take the form of spherical clusters of stars. The more metallic, the older: the lighter elements did not exist in the younger universe.

In 2 billion years all these smaller galaxies and orbiting star clusters will end up colliding with the Milky Way, so that our neighborhood in the universe will be made up of fewer but larger galaxies. From there the next big event will be in 4,000 million years, when the Andromeda galaxy ended up absorbing us.

Image | fencing