Some say that Clint Eastwood is the oldest star in the universe, but researchers at The Australian National University (ANU) have discovered one that is even older–a staggering 13.6 billion years old.
The ANU SkyMapper Telescope found the star, which was born only 100 to 200 million years after the Big Bang, to be remarkably close on the galactic scale. The star, with the abbreviated name SM0313, is just 6,000 light years away, which is well within the borders of our own Milky Way galaxy.
“This is the first time that we’ve been able to unambiguously say we’ve found the chemical fingerprint of a first star,” says Stefan Keller, lead researcher for the ANU Research School of Astronomy and Astrophysics.
This discovery is not only important in mapping the structure of the early Universe, but also has implications for the structure of early stars. Present-day stars like our sun have radically different ingredients of creation. Our sun, Keller explains, is created by “taking the basic ingredients of hydrogen and helium from the Big Bang and adding an enormous amount of iron–the equivalent of about 1,000 times the Earth’s mass.”
However, the creation of SM0313 is done with only an “Australia-sized asteroid of iron and lots of carbon.” This difference in creation tells scientists a lot “about the nature of the first stars and how they died,” Keller explains.
It was previously thought that very old stars died in hugely violent explosions, which “polluted huge volumes of space with iron,” says Keller. However, this ancient star only showed signs of pollution with lighter elements, like carbon and magnesium.
The chemical composition of this new star shows that it formed from the supernova of a primordial star 60 times as massive as our sun, explains the ANU news.
The discovery counters a current theory that primordial stars die in extremely violent explosions, which pollute huge volumes of space with iron. The recent discovery “indicates the primordial star’s supernova explosion was of surprisingly low energy,” Keller says. “Although insufficient 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.”
“There’s likely to be more stars like this, but they are very hard to find,” Mike Bessell, the astronomer who first spotted the old star, said. Bessell and Keller confirmed the discovery using the Magellan Telescope in Chile.
SM0313 is located in the southern constellation of Dorado, in between the large and small Magellanic Clouds, though it can’t be viewed by the naked eye.
The discovery was published in the latest edition of the scientific journal Nature.