An ancient star has been discovered right in our own galaxy

Claire Tourigny November 8, 2018

One of the oldest stars in the universe has been discovered, and it’s located right within our own galaxy.

An ancient star has been discovered right in our own galaxy

Astronomers could confirm its age by analysing the metal components, because the older a star is, the fewer metals it contains. This is because heavy elements simply didn’t exist in the early days of our universe – they were created by the explosions of supernovae as the universe aged. The first generations of stars were made up mostly of helium, hydrogen, and lithium. And now, armed with this knowledge, astronomers have found one of these ancient stars hiding right under our nose in the Milky Way.

Discovered by a team of researchers using the Magellan Clay Telescope at Las Campanas Observatory, Chile, and the Gemini Observatories in Hawaii, the ancient star is believed to have formed 200 million years after the Big Bang. This makes the star 13.5 billion years old. For context, our own sun hasn’t even hit the big 5 billion yet.

The ancient star, unfortunately named 2MASS J18082002-5104378 B, contains such a tiny amount of heavy metals that researchers believe it could have been a part of the second “generation” of stars formed after the Big Bang.

Our elderly neighbour star has spent the past couple billions of years hanging out, unnoticed, in a two-star system in the constellation Ara. Since 2MASS is smaller and fainter than its buddy, it was the second of the two to be discovered. In fact, it was found by accident while the team was searching for black holes. That search came up empty but, in doing so, the team found the little 2MASS J18082002-5104378 B. And, while finding anything so old is undoubtedly exciting, its size has been even more of a hot topic for astronomers.

2MASS J18082002-5104378 B (seriously, they couldn’t give it a better name?) is tiny, only 14% the mass of our sun. For years it was believed that the earliest stars would have had to have been massive, and very short-lived. Up until the late ‘90s, the general consensus was that none of the first generations of stars still existed, since they would have burnt out long ago. But the discovery of 2MASS J18082002-5104378 B proves that the early universe was capable of creating tiny stars that could last for trillions and trillions of years.

According to Kevin Schlaufman, lead author of the paper outlining 2MASS’ discovery (free version here) published in the peer-reviewed Astrophysical Journal, this means that the first stars, the ones born from materials directly created by the Big Bang, might still be out there. “If our inference is correct,” he said, “then low-mass stars that have a composition exclusively the outcome of the Big Bang can exist. Even though we have not yet found an object like that in our galaxy, it can exist.”