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| (James Josephides/Swinburne Astronomy Productions) |
In the early days of the universe approximately 10.8 billion years ago, astronomers have just found a galaxy wearing the battle-scars of a cosmic brawl. It's not a blob or disc of stars, like most galaxies, but a giant doughnut - with a huge hole punched right through its center.
This type of galaxy looked like an eye glared across space. Now, using data from the W.M. Keck Observatory in Hawaii and the Hubble Space Telescope, astronomers have captured a snapshot of its unblinking gaze.
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| A composite image made from multiple single-color Hubble Space Telescope images shows what the galaxy looks like from Earth. (Image credit: Tiantian Yuan/Hubble Space Telescope) |
This classifies it as a rare type of galaxy known as a ring galaxy, and it's rare to even among that type - its shape forged not by internal processes, but a collision that saw its core stripped away as the other galaxy passed through.
The galaxy is called R5519, and it's the first collisional ring galaxy ever found more than a few hundred light-years away - which makes it the only known such object in the early Universe.
Galaxies in the early universe tended to be very active, churning up hot gas and turning it into stars. R5519 is no exception, the researchers said in a statement."It is making stars at a rate 50 times greater than the Milky Way," Tiantian Yuan, an astronomer at Australia's Swinburne University of Technology and lead discoverer of the galaxy, said in the statement. "Most of that activity is taking place on its ring – so it truly is a ring of fire."
Most of the ring-shaped galaxies in our universe form through internal processes, the researchers said. Only 1 in 1,000 in the modern universe forms through collisions. Still, according to the new paper, which was published May 25 in the journal Nature Astronomy, this galaxy's shape does appear to be the result of a collision with another object.
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| (James Josephides/Swinburne Astronomy Productions) |
This monumental collision offers clues about the conditions that prevailed during the early universe, the scientists said.
So, how did R5519's unblinking "Eye of Sauron" shape come into being?
For a ring to form, a galaxy like this has to start as a wide, flat disk of stars and gas, the researchers said. One such disk that formed about 9 billion years ago turned into the spiral Milky Way. Another formed Andromeda, a neighboring galaxy.
But R5519's disk, if it indeed existed before another object punched that hole in its center, would have existed a full 2 billion years earlier, just 3 billion years after the Big Bang.
"This discovery is an indication that disk assembly in spiral galaxies occurred over a more extended period than previously thought," Kenneth Freeman, an Australian National University astronomer and co-author of the paper said in the statement.
That changes how astronomers see the early history of the universe.
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