The fingerprints left by explosion of the first stars in the Universe researchers identified for the first time.

Using data from the European Southern Observatory’s (ESO) Very Large Telescope (VLT), scientists have identified three distant gas clouds, observed when the Universe was only 10-15% of its current age, and with a chemical signature that matches what we expect from first stellar explosions. These findings bring us one step closer to understanding the nature of the first stars that formed after the Big Bang.

Scientists believe that the first stars to form in the Universe were very different from what we see today. When they appeared 13.5 billion years ago, they contained only hydrogen and helium, the simplest chemical elements in nature. These stars, believed to be tens or hundreds of times the mass of the Sun, quickly died in powerful explosions known as supernovae, enriching the surrounding gas for the first time with different chemical elements, such as carbon, oxygen and magnesium. Later generations of stars were born from this enriched gas and in turn ejected heavier elements as they died. “Primordial stars can be studied indirectly by detecting the chemical elements scattered into their environment after their death,” explains Stefania Salvadori, associate professor at the University of Florence and one of the authors of the study, published in the journal “Astrophysical Journal”.

The three distant clouds detected had very little iron, but plenty of carbon, oxygen and magnesium, the imprint of the explosions of the first stars.

With next-generation telescopes and instruments, such as ESO’s upcoming Extremely Large Telescope (ELT) and the ANDES high-resolution spectrograph, scientists will be able to study “many of these rare gas clouds in greater detail, and we will eventually be able to reveal the mysterious nature of the first stars,” notes Valentina D’Ontorico, a researcher at the National Institute of Astrophysics in Italy and one of the authors of the study.