VIDEO: This is what happens when a big galaxy smashes into a small one

Cosmic Giants Meet Galactic Dwarfs. Image: The International Centre for Radio Astronomy Research

When two galaxies collide, the larger one stops the smaller making new stars, according to a study.

The research of 20,000 merging galaxies also found that when two of the same size collide, both produce stars at a much faster rate.

Astrophysicist Luke Davies, from the University of Western Australia, says the nearest major galactic neighbour, Andromeda, is hurtling on a collision course with the Milky Way at 400,000 kilometres an hour.

“Don’t panic yet, the two won’t smash into each other for another four billion years or so,” he says. “But investigating such cosmic collisions lets us better understand how galaxies grow and evolve.”

Here’s an animation show what happening when galaxies collide:

Previously astronomers believed that when two galaxies smash into each other their gas clouds get churned up and seed the birth of new stars much faster than before.

However, Dr Davies’ research using the Galaxy and Mass Assembly (GAMA) survey observed using the Anglo-Australian Telescope in regional New South Wales suggests this idea is too simplistic.

“When two galaxies of similar mass collide, they both increase their stellar birth rate,” Dr Davies says.

“However when one galaxy significantly outweighs the other, we have found that star formation rates are affected for both, just in different ways.

“The more massive galaxy begins rapidly forming new stars, whereas the smaller galaxy suddenly struggles to make any at all. This might be because the bigger galaxy strips away its smaller companion’s gas, leaving it without star-forming fuel or because it stops the smaller galaxy obtaining the new gas required to form more stars.”

The study was released in the journal Monthly Notices of the Royal Astronomical Society published by Oxford University Press.

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