Spiral v. Clumpy Galaxies: Study Offers New Spin On Star-Forming Galaxies

Why are some galaxies "clumpy" instead of spiral? A team of researchers are shedding new light on some galaxies' "clumpiness" compared to spiral shaped galaxies. Apparently, it is due to a low spin, according to a study.

The researchers' new finding counters a previous theory that high levels of gas caused clumpy galaxies and also provides new data on the birth of many stars in the universe. The universe was full of clumpy galaxies ten billion years ago, and over time they eventually evolved into regular objects. Many stars, including our five-billion-year-old sun were most likely born inside clumpy formations, according to the researchers.

"The clumpy galaxies produce stars at phenomenal rates. A new star pops up about once a week, whereas spiral galaxies like our Milky Way only form about one new star a year," Dr. Danail Obreschkow, lead author of the study from The University of Western Australia, said in a news release.

The research team focused on rare galaxies called DYNAMO galaxies. These galaxies were quite clumpy when they were seen "only" 500 million years in the past. Obreschkow claimed that looking at galaxies 500 million years ago was like looking at a passport photo from a year ago.

"We see that galaxy the way it probably looks now... something could have happened to it but it's very unlikely. The galaxies that are 10 billion light years away, that's comparable to a picture from when you were three or four years old, that's very different," Obreschkow said.

The Keck and Gemini observatories in Hawaii were used to measure the galaxies' spin and millimetre and radio telescopes were used to measure the amount of gas that these galaxies contain.

The DYNAMO galaxies had a low spin, which was responsible for the galaxies' clumpiness.

"While the Milky Way appears to have a lot of spin, the galaxies we studied here have a low spin, about three times lower," Obreschkow said.

The researchers claimed that the spin of the initial cloud of gas has an essential role in galaxy formation.

"This novel result suggests that spin is fundamental to explaining why early galaxies are gas-rich and lumpy while modern galaxies display beautiful symmetric patterns," said Karl Glazebrook, coauthor of the study.

The findings of this study were published in the journal Arxiv. 

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