A team of astronomers have found what could be one of the universe's oldest stars, almost entirely made of materials formed by the Big Bang.

Residing in the same part of the Milky Way galaxy as our own solar system, the star is believed to be up to 13.5 billion years old which is evidenced by its extremely low metal content, or metallicity, Xinhua news agency reported.

According to co-author Andrew Casey, it was previously believed that the first stars that formed in the universe could not possibly still exist today.

"The findings are significant because for the first time we have been able to show direct evidence that very ancient, low mass stars do exist, and could survive until the present day without destroying themselves," Casey said.

The metallicity of stars increases as they are born and die, in a cycle which results in the creation of more and more heavy metals, with the Earth's sun being around 100,000 generations down that line and holding a metal content roughly equal to 14 Jupiters.

Stars created at the beginning of the universe, however, would have consisted entirely of elements like hydrogen, helium and small amounts of lithium - meaning the extremely low metallicity of the newly discovered star, about the same as the planet Mercury.

This suggests that it could be as little as one generation removed from the beginning of the universe, the researchers noted.

Up until around 1990, scientists believed that only massive stars could have formed in the early stages of the universe, and could never be observed because they burn through their fuel so quickly and die.

However, the new study has shown that it is possible for low mass stars to last as long as the 13 billion years since the Big Bang -- Red Dwarf stars for instance, which have a fraction of the mass of the sun, are thought to live for trillions of years.