A team of astronomers announces the incredible discovery in our Galaxy of a 13.5 billion-year-old star, one of the oldest in the universe. Details of the study will be published shortly in The Astrophysical Journal.
It is a true relic of the Universe, an object already present some 300 million years after the Big Bang, which marks the beginning of the expansion of our world. Called 2MASS J18082002-5104378 B, the star also has the lowest metal content of all the stars ever discovered (the first metals were formed only after the first generation of stars). Its mass is also very small, just enough to allow it to fuse its hydrogen (and therefore to shine).
“This discovery teaches 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,” said Astrophysicist Andrew Casey of Monash University in Australia. These ancient stars could be formed from very small amounts of material, which means that some of these relics dating back to shortly after the Big Bang could still exist today. This gives us a new point of view on the formation of stars in the primitive universe! ”
Scientists have long believed that the very first stars of the Universe were very massive (and thus with a very short life span), this new discovery, however, confirms that low-mass stars could have also evolved at this time. By tracking them, it is now possible to learn about the conditions that prevailed only a few hundred million years after the Big Bang.
“These stars are extremely rare. It’s like looking for a needle in a haystack,” says the researcher. “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 were formed at the beginning of the Universe.”
A team of astronomers have already announced to have observed stars forming only 250 million years after the Big Bang (2% of the current age of the Universe). To go even further back in time, new instruments will be needed, in particular the James Webb Space Telescope (JWST), whose launch is planned in 2021. The objective will then be to be able to date exactly when was born the very first star of the very first galaxy.