Australian astronomers have discovered the oldest known star in the Universe, formed shortly after the Big Bang 13.7 billion years ago.
The ancient star is relatively close by, about 6,000 light years from Earth.
Scientists can now study the chemistry of the first stars, giving a clearer idea of what the universe was like in its infancy.
“This is the first time that we’ve been able to unambiguously say that we’ve found the chemical fingerprint of a first star,” said lead researcher Dr Stefan Keller of the ANU Research School of Astronomy and Astrophysics.
The star was discovered using the ANU SkyMapper telescope at the Siding Spring Observatory in New South Wales as it conducts a five-year project to produce the first digital map of the southern sky.
The ancient star is one of the 60 million stars photographed by SkyMapper in its first year.
The composition of the newly discovered star shows it formed in the wake of a primordial star, which had a mass 60 times that of our Sun.
To make a star like the Sun, 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.
“To make this ancient star, you need no more than an Australia-sized asteroid of iron and lots of carbon,” said team member Professor Mike Bessell.
“It’s a very different recipe that tells us a lot about the nature of the first stars and how they died.”
It was previously thought that primordial stars died in extremely violent explosions which polluted huge volumes of space with iron.
But the ancient star shows signs of lighter elements such as carbon and magnesium, and no sign of pollution with iron.
“This indicates the primordial star’s supernova explosion was of surprisingly low energy. Although sufficient to disintegrate the primordial star, almost all of the heavy elements such as iron, were consumed by a black hole that formed at the heart of the explosion,”said Professor Bessell.
The result may resolve a long-standing discrepancy between observations and predictions of the Big Bang.
The discovery was announced today in the journal Nature.
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