Oldest known star in the Universe discovered

Written by PTI | Melbourne | Updated: Feb 10 2014, 21:31pm hrs
StarThe star was discovered using the ANU SkyMapper telescope at the Siding Spring Observatory. Reuters
Australian scientists have discovered the oldest known star in the Universe, which formed shortly after the Big Bang 13.7 billion years ago.

The discovery of the star, located around 6,000 light years from Earth, has allowed astronomers for the first time to 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 The Australian National University Research School of Astronomy and Astrophysics.

"This is one of the first steps in understanding what those first stars were like. What this star has enabled us to do is record the fingerprint of those first stars," Keller said.

The star was discovered using the ANU SkyMapper telescope at the Siding Spring Observatory, which is searching for ancient stars as it conducts a five-year project to produce the first digital map of the southern sky.

"Finding such needles in a haystack is possible thanks to the ANU SkyMapper telescope that is unique in its ability to find stars with low iron from their colour," Keller said.

Keller and colleagues confirmed the discovery using the Magellan telescope in Chile.

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 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," Keller said.

"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," Keller said.

Keller said it was previously thought that primordial stars died in extremely violent explosions which polluted huge volumes of space with iron.

However, the ancient star shows signs of pollution with 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," Keller said.

The discovery was published in the journal Nature.