Australasian Science: Australia's authority on science since 1938

A New Spin on Star-Forming Galaxies

By Dave Reneke

Astronomers calculate that black holes at the heart of galaxies could swell to 50 billion times the mass of the Sun, and determine why some galaxies are “clumpy” rather than spiral in shape.

The full text of this article can be purchased from Informit.

Australian researchers have discovered why some galaxies are “clumpy” rather than spiral in shape, and it appears low spin is to blame. The finding challenges an earlier theory that high levels of gas cause clumpy galaxies, and sheds light on the conditions that brought about the birth of most of the stars in the universe.

Ten billion years ago the universe was full of clumpy galaxies, but these developed more regularity as they evolved. Dr Danail Obreschkow of The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) said the majority of stars in the sky today, including our five-billion-year-old Sun, were probably born inside these clumpy formations. “The clumpy galaxies produce stars at phenomenal rates,” Obreschkow said. “A new star pops up about once a week, whereas spiral galaxies like our Milky Way only form about one new star a year.”

ICRAR and Swinburne University astronomers focused on a few rare galaxies, known as the DYNAMO galaxies, that still look clumpy even though they’re observed “a mere” 500 million years in the past. Obreschkow said this was like looking at a passport photo taken only last year whereas “the galaxies that are 10 billion light years away, that’s comparable to a picture from when you were 3 or 4 years old. That’s very different.”

The team used the Keck and Gemini...

The full text of this article can be purchased from Informit.