The earliest stars were destroyed by "super-supernovas," according to astronomers.

Using a quasar that was 13.1 billion years old, the team looked at chemical traces of Population III stars.

A portrait of a Population III star as it would have appeared 100 million years after the Big Bang by an artist. (Image source: Spaceengine, NOIRLab, NSF, AURA, and J. da Silva)

One of the earliest stars, which was born when the universe was just 100 million years old and exploded in a "super-supernova," may have left chemical traces for astronomers to discover.

The titanic supernova explosions that claimed the lives of these first-generation stars—known as Population III stars—sowed chemical elements into the universe during their lifetimes. Understanding how these earliest stars enriched the universe with heavy elements is essential to comprehending its evolution over its 13.7 billion-year history because this material was then incorporated into the subsequent generation of stars, planets, and even us.

An extremely distant quasar, a super bright object powered by a massive black hole, was analyzed by a group of researchers on the Hawaiian island of Hawai'i using the 8.1-meter Gemini North telescope. They discovered a cloud around the object that had a distinct chemical signature.

The chemical elements in the cloud were deduced by the researchers, who discovered an unusually high ratio of iron to magnesium—ten times higher than the sun's equivalent ratio. Astronomers believe that this debris cloud could only be the result of a pair-instability supernova, a remarkably powerful supernova that occurred when a first-generation star with a mass 300 times greater than the sun exploded.

Although scientists have yet to observe a pair-instability supernova, they speculate that these massive explosions take place when massive stars with masses ranging from 150 to 250 times that of the sun reach their end of life.

According to some theories, photons in a star's center spontaneously transform into electrons with a negative charge and positrons with a positive charge during this massive cosmic explosion. During their lifetimes, this brings an end to the radiation pressure that supported stars against the inward force of gravity. As a direct consequence of this, the star experiences gravitational collapse, which in turn sets off a supernova explosion that tears away the star's outer layers.

An illustration of a distant quasar that astronomers use to study the first generation of stars.(Image source: Spaceengine, NOIRLab, NSF, AURA, and J. da Silva)

However, pair-instability supernovas do not release all of their material into space, unlike ordinary supernovas, which leave behind stellar remnants in the form of neutron stars or black holes.

Because stellar remnants cannot be found, these supernovas can only be tracked in one of two ways: either by spotting the chemical signature of the material they release or by directly witnessing them as they occur, which is highly unlikely given the vastness of space.

Yuzuru Yoshii, a co-author of the study and an astronomer at the University of Tokyo, stated in a statement, "It was obvious to me that the supernova candidate for this would be a pair-instability supernova of a Population III star, in which the entire star explodes without leaving any remnant behind. "The discovery that a pair-instability supernova of a star with a mass approximately 300 times that of the sun yields a ratio of magnesium to iron that is consistent with the low value we derived for the quasar pleased and surprised me.

Spotting the chemical signature of a first-generation star

Yoshii searched for signs of exploded Population III stars using previous observations made by the 8.1-meter Gemini North telescope using the Gemini Near-Infrared Spectrograph (GNIRS) with co-authors Timothy Beers of the University of Notre Dame and fellow University of Tokyo astronomer Hiroaki Sameshima.

Elements leave distinct "fingerprints" on the light that passes through an atmosphere or cloud because they absorb and emit light at specific wavelengths. This light is taken by spectrographs like GNIRS, which use this fingerprint to identify elements and determine the cloud's chemical composition. But it's still hard to figure out how much of an element is there because the brightness of a signature can be affected by more than just its abundance.

An illustration of a distant star going supernova that is 300 times larger than the sun.(Image source: Spaceengine, NOIRLab, NSF, AURA, and J. da Silva)

An approach based on the intensity of quasar light spectrum wavelengths was developed by astronomers at the University of Tokyo to address this issue. The scientists were able to determine the abundance of elements in the clouds surrounding that quasar using this method, revealing an unusually high ratio of iron to magnesium.

This, according to Yoshii and the team, is the most definitive sign yet of a pair-instability supernova and a Population III star. The team wants to look at similar quasar clouds to see if they have these characteristics as well.

Additionally, despite the fact that high-mass Population III stars would have died out long ago, their chemical signatures may be detectable closer to home. Since the pair-instability signature may persist for a considerable amount of time, the team hypothesizes that the remains of long-dead stars may also be imprinted on objects in the local universe.

We are now aware of what to look for; Beers stated in the same statement, "We have a path. "There should be evidence for this if it occurred locally in the very early universe, as it should have."