One of the oldest stars has just found herself mysteriously hidden in our galactic court | MNN

Usually, if you want to look at one of the oldest stars of the known universe, you have to look very far, and go back in time, into the confines of the cosmos. Indeed, the oldest stars are those that formed right after the Big Bang, 13 billion years ago. The last place you would expect to find any of these ancient stars is here, in our own galaxy, the Milky Way.

So you can imagine the surprise of astronomers who have recently discovered a faint glow in the orbit of the thin disk of the Milky Way – the dense plan of rotation of the galaxy – that bears all the marks of a very former star, reports Science Alert. .

The best way to know if a star is one of the oldest stars is to look at its metal content. This is because at the very beginning of the universe, there were no metals. It took the first generations of stars to forge the first metals before they started incorporating them into the contents of newer stars. In fact, the younger the star, the higher its metal content.

So when scientists discover a low-grade metal star, they know it must be old. And that's exactly what was found in this newly discovered weak star, now called 2MASS J18082002-5104378 B. The metal content of this star is so low that it is considered the lowest metallicity of any star ever discovery.

Rework the history of the universe

"We have never discovered a star of such low mass and composed of so few grams of metals," said astrophysicist Andrew Casey of Monash University in Australia. "This discovery tells us that the very first stars in the universe do not necessarily have to be massive stars that have been dead for a long time – these ancient stars could form from very small amounts of material, which means some of these relics soon after the big bang might still exist today.This gives us a new perspective on the formation of stars in the early Universe! "

In other words, for a star to last just after the Big Bang and still have fuel to burn today, it would be a very small, weak star. This is because the biggest and brightest stars go out too quickly. This is the version of the universe of "the bigger they are, the harder they fall". The problem is that scientists have never thought that small stars of this kind were produced much later in the history of the universe.

Not only have these theories been refuted through 2MASS J18082002-5104378 B, but it seems like one of the oldest stars in the universe is hiding in our garden from the beginning.

The star is so weak that it is not really a surprise that we took so long to discover. In fact, the only reason he was spotted is that he has a brighter binary companion. Of course, this means that there is a chance that other old stars are also hovering in our galaxy; it is enough to squint, so to speak, to look for them.

"These stars are extremely rare – it's a bit like looking for a needle among an acre of haystacks," Casey said. "But with huge amounts of data coming from terrestrial and space telescopes, the future is bright: we are closer than ever to understanding how stars formed in the early Universe."

One of the oldest stars has just been mysteriously hidden in our galactic courtyard

A low-grade metal star is old, and a newly discovered star, 2MASS J18082002-5104378 B, has the lowest metallicity of any stars we have found.