Astronomers have discovered the remains of the very first stars in the universe

(ORDO NEWS) — Analyzing data from the Gemini North telescope, an international team of scientists appear to have found traces of the very first stars that appeared just hundreds of millions of years after the Big Bang.

Although the stars themselves of the first generation are long gone, the remnants of their supernovae indirectly confirm the correctness of modern cosmological models of the evolution of the Universe.

According to modern ideas in cosmology, after the Big Bang, as the Universe expanded, the so-called primary nucleosynthesis took place. As a result, the first chemical elements were formed – mainly hydrogen and helium.

The stars of the first generation, also known as stellar population III, were born precisely from such a primary gas, practically not including metals (in cosmology, these are any elements heavier than helium).

The very first stars must have been extremely massive, on the order of hundreds of solar masses, and formed just 100 million years after the Big Bang.

Due to their size, these giants should have had a very short lifespan, only about a million years, which is more than ten thousand times shorter than the estimated lifespan of our Sun.

At the end of their life cycles, first-generation stars burst into exceptionally bright supernovae, filling interstellar space with a characteristic mixture of heavy chemical elements.

Despite decades of diligent search, astronomers still have not found direct evidence of the existence, described so far only in theory, of the first stars in the universe.

A new attempt to detect, if not the stars of the first generation, then at least their remnants, was undertaken by an international group of scientists from Japan, the USA and Australia.

The researchers described their observations in an article published in The Astrophysical Journal .

Using data from the Gemini North telescope, the authors analyzed the signal coming from the most distant known quasar, ULAS J1342+0928, located in the constellation Bootes.

In the analysis, the scientists used a new method to determine the chemical elements contained in the clouds of gas surrounding the quasar.

The elemental composition of the gas was extremely atypical: the iron content there was 20 times higher than that of the Sun, and the ratio of magnesium to iron content turned out to be significantly lower than that of any other gas cloud in closer quasars.

The detected features allowed scientists to assume that the cloud was formed as a result of the explosion of a star of the first generation of a pair-unstable supernova.

Such events occur when photons in the interiors of massive stars (150–250 times more massive than the Sun) begin to generate electron-positron pairs, which provokes the collapse and subsequent explosion of a supernova.

“It was clear to me that a supernova candidate would be a pair-unstable population III supernova, as a result of which the star is completely destroyed, leaving behind neither a neutron star nor a black hole,” said Yuzuru Yoshii, lead author of the study.

“I was pleased and somewhat surprised to find that simulations of a pairwise unstable supernova with a mass of about 300 times the mass of the Sun provide a ratio of magnesium to iron that is consistent with the low value obtained for the signal from the quasar.”

If the researchers really managed to find evidence of the existence of one of the stars of the first generation, this will serve as another indirect proof of the correctness of modern cosmological models of the evolution of the Universe.

However, first we need to check the interpretation of the signal received from the ULAS J1342+0928 quasar proposed in this work more carefully. In addition, much more observational data will be needed to find other objects with similar characteristics.


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