Scientists discover rare 'ring of fire' galaxy

A team of scientists has discovered a galaxy that looks like a "cosmic ring of fire" and could help us understand more about how galactic structures form and evolve.

The incredibly rare kind of galaxy has a similar mass to our Milky Way but is shaped like a doughnut with a hole in the middle, according to a press release from the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D).

Astronomers from the institution managed to capture an image of the galaxy and can now reveal what it looked like 11 billion years ago.

"It is a very curious object that we've never seen before," said lead researcher Tiantian Yuan, from the centre, in a statement. "It looks strange and familiar at the same time."

The galaxy, which has been named R5519, is 11 billion light-years from our Solar System.

The hole at its centre has a diameter two billion times longer than the distance between Earth and the sun, according to a press release issued yesterday.

"It is making stars at a rate 50 times greater than the Milky Way," said Dr Yuan. "Most of that activity is taking place on its ring -- so it truly is a ring of fire."

The discovery is described in full in the journal Nature Astronomy.

Dr Yuan and a group of colleagues from around the world used spectroscopic data to identify the galaxy, and evidence suggests it may be the first "collisional ring galaxy" located in the early universe.

Collisional ring galaxies form after smashing into other galaxies.

The paper could help astronomers understand how our own Milky Way formed, said co-author Kenneth Freeman from the Australian National University.

For a collisional ring galaxy to form from the collision of two galaxies, a so-called "thin disk" of material must be present in one galaxy before the collision occurs, said Professor Freeman.

Spiral galaxies like the Milky Way all have thin disks, and its disk only started forming around nine billion years ago, he said, but this collisional ring galaxy is some 11 billion years old.

"This discovery is an indication that disk assembly in spiral galaxies occurred over a more extended period than previously thought," Professor Freeman said.