The discovery of the heavenly body, which formed about 13.6bn years ago, has allowed astronomers to study the chemistry of the first stars.
Lead researcher Dr Stefan Keller of the ANU’s Research School of Astronomy and Astrophysics called the find a “one in a 60m chance”.
“I was pleasantly surprised,” Keller said. “It was very much a needle-in-a-haystack situation.”
The team discovered the star using the university’s SkyMapper telescope at the Siding Spring observatory near Coonabarabran in northern New South Wales.
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.
At the heart of the telescope is a digital camera that uses 268m 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,” 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.”
He 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 had 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.
Keller and his team’s discovery, which was confirmed using the Magellan telescope in Chile, is published in the latest edition of Nature.