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article imageOldest known star discovered by Australian astronomers

By Megan Morreale     Feb 10, 2014 in Science
Australian astronomers have discovered the oldest known star in the universe through what the lead researcher describes as a "needle-in-a-haystack" situation.
A team of scientists at the Australian National University discovered the oldest known star in the universe, a heavenly body weighing in at 13.6 billion years old.
The star has given astronomers the opportunity to study the chemistry of the first known stars, hoping to lead to more information about the beginnings of the universe, as the Guardian reported..
Lead researcher Dr. Stefan Keller of ANU's research school of Astronomy and Astrophysics commented on the unlikelihood of discovering the body, calling it a "one in 60 million chance."
“Just by imaging the colours of stars, we can tell which stars are prime candidates of being the oldest,” Keller said. “We can tell how much iron it has – the more iron, the younger the star. In the case of the star we have announced, the amount of iron present is a factor of at least 60 times less than any other star.”
The star was spotted by the wide-field telescope being used to search for ancient stars as part of a project hoping to produce the first comprehensive digital map of the sky for the last five years.
The defined star has been described as a time capsule, providing new information that could change current beliefs about earlier stars, specifically about what there iron contents can tell us.
Keller explains that because of the discovery of this new star, the old theory that the oldest stars would have to be extremely massive may no longer be viable, as reported by RT.
“It's giving us insight into our fundamental place in the universe. What we're seeing is the origin of where all the material around us, that we need to survive, came from,” Keller said. “What that means is we had a long-held theory that the first stars to form would be extremely massive because they are formed out of pure hydrogen and helium,” said Keller, adding that ‘spectral portrait’ of the newly found ancient star reveals traces of pollution with light elements like carbon and magnesium, but has no sign of iron whatsoever. A star is like an onion - it has all these layers and the heaviest material like iron is right down in the core."
This new evidence could mean that each new generation of stars would contain more iron and be more massive, meaning that the less iron there is in a star's light spectrum, the older it is.
Professor Mike Bessell, the man who spotted the star while analyzing some data from the telescope, said that its spectrum only contained a handful of elements including hydrogen, carbon, magnesium and calcium, which makes it radically different from our own suns composition as well as that of other younger stars.
"There's likely to be more stars like this, but they are very hard to find," Bessell said. "We have to sort through vast amounts of data to find the very few of them that are out there. It's a needle in a haystack."
Modern cosmological science claims that the universe came into being as a result of a Big Bang event around 13.7 billion years ago. Our own sun is roughly 13.2 billion years old. This 13.6 billion year old star could help scientists unlock some answers about how the universe formed.
The discovery of the star was confirmed using the Magellan telescope in Chile. It's composition shows that it formed in the wake of a primordial star, which has a mass 60 times that of our own sun.
Dr. Keller explained that it was previously thought that primordial stars died in extremely violent explosions which would then pollute huge volumes of space with Iron. The chemical makeup of this star, explained by professor Bessell, starts to put together an entirely different story.
“To make a star like our Sun, you take the basic ingredients of hydrogen and helium from the Big Bang and add an enormous amount of iron – the equivalent of about 1,000 times the Earth’s mass,” said Dr. Keller as reported by RedOrbit. "To make this ancient star, you need no more than an Australia-sized asteroid of iron and lots of carbon. It’s a very different recipe that tells us a lot about the nature of the first stars and how they died.”
The ancient star is locates about 6,000 light years from Earth, which is relatively close in astronomical terms. It was one of the first 60 million stars photographed by the SkyMapper in the first year.
“This is the first time we've unambiguously been able to say we've got material from the first generation of stars," Keller said. "We're now going to be able to put that piece of the jigsaw puzzle in its right place,” the astronomer told Reuters.
The discovery was published in the latest edition of the journal, [i]Nature[/i].
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