When two different sized galaxies smash together, the larger galaxy stops the smaller one making new stars, according to a study of more than 20,000 merging galaxies.
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| Source: ICRAR |
The research also found that when two galaxies of the same size collide, both galaxies produce stars at a much faster rate.
Previously, astronomers thought that when two galaxies smash into each other their gas clouds—where stars are born—get churned up and seed the birth of new stars much faster than if they remained separate.
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.
He says whether a galaxy forms stars more rapidly in a collision, or forms any new stars at all, depends on if it is the big guy or the little guy in this galactic car crash.
“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.”
