A team of scientists at the Australian National University (ANU) has discovered the oldest known star in the universe.
The discovery of the heavenly body, which formed about 13.6 billion years ago, has allowed astronomers for the first time to study the chemistry of the first stars.
Lead researcher Dr Stefan Keller of ANU's research school of astronomy and astrophysics called the find a "one in a 60 million chance".
"I was pleasantly surprised (when we found the star)," Dr Keller said.
"It was very much a needle-in-a-hay-stack situation.
"There was one in 60 million chance of finding the star."
The team discovered the star using the university's SkyMapper telescope at the Siding Spring Observatory near Coonabarabran in northern NSW.
The wide-field telescope is being used to search for ancient stars as part of a project to produce the first digital map of the southern sky.
And at the heart of the telescope is a digital camera that uses 268 million pixels to capture an area of sky 29 times larger than the full moon every minute.
"Just by imaging the colours of stars, we can tell which stars are prime candidates of being the oldest," Dr Keller explained.
"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."
Dr Keller described the discovery as a "time capsule", providing new information that defied earlier beliefs about some of the first stars.
He said the newly-discovered star formed in the wake of a primordial star, which had a mass of 60 times that of the sun and died in a supernova explosion.
"The explosion was of surprisingly low energy, such that although the (primordial) star disintegrated, almost all of the heavier elements, such as iron, that form near the core of the star, were swallowed by a black hole," Dr Keller said.
"This is not what was expected. (Previously) it was thought that the first stars would undergo titanic supernova explosions that spread iron over vast volumes of space.
"Our findings show that iron levels remained low for a longer time than previously thought, enabling more massive first stars to form and die."
Dr Keller and his team's discovery, which was confirmed using the Magellan telescope in Chile, is published in the latest edition of the journal Nature.
