Scientists have finally identified fingerprints left by the explosion of 'first stars' in our Universe

How were the fingerprints identified?

The team studied three gas clouds that existed in the early universe (when it was only 10-15 percent of its current age). According to the study, the chemical composition of these gas clouds corresponded to the first star explosions. Simply put, the three distant gas clouds contained carbon, oxygen, and magnesium, but less amount of iron — the signature expected from the first star explosions. 

“To search for the telltale sign of these very first stars that exploded as low energy supernovae, the team, therefore, looked for distant gas clouds poor in iron but rich in the other elements. And they found just that: three faraway clouds in the early Universe with very little iron but plenty of carbon and other elements — the fingerprint of the explosions of the very first stars,” explained the official statement.  

However, it is not as simple as it may appear. Scientists have to study bright light beams that have traveled the entire length of the universe to reach us. 

For this study, the researchers used light from quasars that travel through the universe. As per the statement, the various chemical elements released leave an imprint on the light as it passes through leftover gas clouds in the journey. The Very Large Telescope (VLT) of the European Southern Observatory was used for this study. 

What does the study signify?

Scientists hypothesized that the primordial, or first stars were very different from the ones they see in the universe today. This knowledge is critical to understanding the properties of the first stars that formed soon after the Big Bang. And how the birth of these first stars shaped the universe into what it is today. 

Astronomers have been able to study these first stars, thanks to the volatile cosmic explosions known as supernovae. “Primordial stars can be studied indirectly by detecting the chemical elements they dispersed in their environment after their death,” said Stefania Salvadori, Associate Professor at the University of Florence and co-author of the study. 

Some of these massive explosions could have released chemical elements in the surrounding space such as carbon, oxygen, and magnesium (present in the outer star layers). And the ashes of these exploding stars enrich the surrounding gas, giving rise to the next generation of stars.

In fact, this type of chemical composition has also been found in many old stars present in the Milky Way galaxy. This suggests that some of these old stars were formed directly from the elements of the firstborn stars in the early universe.

The new study opens up the way to examine rare gas clouds in order to better understand the mysterious nature of the first stars. 

The results have been published in the Astrophysical Journal.