Diamond-shaped galaxy discovered

By AAP with AG staff 20 March 2012
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A new type of galaxy that resembles an emerald-cut diamond has been discovered by astronomers.

A RARE GALAXY SHAPED like an emerald-cut diamond has been discovered by astronomers.

The international team from Australia, Finland, Germany and Switzerland found the rare rectangular-shaped galaxy in a group of 250 galaxies about 70 million light-years from Earth.

“In the Universe around us, most galaxies exist in three forms: spheroidal, disc-like, or lumpy and irregular in appearance,” says Associate Professor Alister Graham from Swinburne University of Technology.

“It’s one of those things that just makes you smile because it shouldn’t exist, or rather you don’t expect it to exist. It’s a little like the precarious Leaning Tower of Pisa or the discovery of some exotic new species which, at first glance, appears to defy the laws of nature,” he says.

Emerald-cut diamond galaxy maybe two merged spirals

The galaxy was detected in an image taken from the Japanese Subaru Telescope and also observed from the Keck Telescope in Hawaii. The Hawaii observations showed a fast-spinning, thin disc with a side-on orientation at the centre of the galaxy.

“One possibility is that the galaxy may have formed out of the collision of two spiral galaxies,” says study co-author Professor Duncan Forbes, also from Swinburne. “While the pre-existing stars from the initial galaxies were strewn to large orbits creating the emerald-cut shape, the gas sank to mid-plane, where it condensed to form new stars and the disc that we have observed.”

The astronomers have been able to get useful information from this galaxy for modelling others.

Dwarf-like galaxy status

The team believes the emerald-cut galaxy was difficult to find because of its dwarf-like status. It has 50 times fewer stars than the Milky Way galaxy.

“Curiously, if the orientation was just right, when our own disc-shaped galaxy collides with the disc-shaped Andromeda galaxy about three billion years from now we may find ourselves the inhabitants of a square looking galaxy.”

Details have been published in the scientific publication, The Astrophysical Journal.