Astronomers edge closer to discovering the Universe's first stars

Astronomers have made a groundbreaking discovery in the search for the first stars that ever formed in the Universe. Using the European Southern Observatory's Very Large Telescope (VLT), they have detected three distant gas clouds with chemical imprints of the explosion of these first stars.

"For the first time ever, we were able to identify the chemical traces of the explosions of the first stars in very distant gas clouds," says Andrea Saccardi, a PhD student at the Observatoire de Paris - PSL, and the lead author of this study.

The first stars that formed in the Universe, around 13.5 billion years ago, were different from the stars we see today as they only contained hydrogen and helium. These massive stars quickly died in powerful supernovae explosions, which enriched the surrounding gas with heavier elements for the first time. Later generations of stars formed from this enriched gas and in turn ejected heavier elements as they died.

Using VLT data, the researchers found three gas clouds in the early Universe, when it was just 10-15% of its current age, that matched the chemical composition expected from the explosions of the first-generation stars. The first supernovae released different chemical elements, including carbon and oxygen, but not heavier elements like iron.

To detect the first stars that exploded as low-energy supernovae, the team searched for gas clouds poor in iron but rich in other elements. They were able to identify three distant clouds in the early Universe that were rich in other elements but lacked iron - exactly the signature expected from the explosions of the first stars.

"Our discovery opens new avenues to indirectly study the nature of the first stars, fully complementing studies of stars in our galaxy," says Stefania Salvadori, Associate Professor at the University of Florence and co-author of the study.

Their findings are published today in the Astrophysical Journal.

🚨 #BreakingNews We are one step closer to finding the first stars that ever formed in the Universe! Using ESO's Very Large Telescope, astronomers have found three distant gas clouds with the fingerprints of the explosions of these first stars💥☁️🐾 Illustration 👇 1/ pic.twitter.com/Klfob8S7BT

— ESO (@ESO) May 3, 2023