When we look at the night sky, we see several dots in the sky flickering. These points are stars present in our galaxy, the Milky Way. The Earth itself orbits a star, the Sun, which was essential to sustaining life on our planet.. At Stars are important parts of our Universe.
Stars produce chemical elements through the process of fusion and even during their death. Each star has a percentage of metallicity – in astronomy, metallicity is any element that is not hydrogen or helium. However, the first stars were to be born in a universe that contained only hydrogen and helium.
The stars that have just been born These two elements are called population III stars.. Until recently, an example of this type of star had never been found and remained one of astronomy’s great mysteries. Last week, James Webb may have found evidence of a star and may have solved this decades-old mystery.
Stars are born after clouds of dust and gas collapse. It is natural that in the process of formation the star has in its composition such elements as oxygen and even iron. The degree of metallicity defines to which type of population this star belongs.
Elements that have an atomic number greater than 2 are called metals in astronomy.
An example of a population I star is the Sun itself. This population consists in the youngest stars in the Universethey are newly formed and millions to billions of years old.
Population I stars have a high metal content. This is due to the fact they are formed from clouds that already contain elements other than hydrogen and helium. This population of stars includes stars ranging from a few fractions of the Sun’s mass to a few tens.
The stars we see in the night sky, in general, are stars of this population.
Population II stars are the second generation of stars in the Universe. These are stars that do not have a high degree of metallicity. but it is still possible to find other elements, in addition to hydrogen and helium, in its composition.
Most Population II stars today are red dwarfs, because The most massive stars in this population have already reached the end of their lives.becoming white dwarfs, neutron stars or stellar black holes.
Population II stars are present in the bulge and halo of galaxies. These are older, redder stars.
Finally, the first population of stars is named Population III, which seems contradictory. This population has no metals in its composition and is only formed of hydrogen and helium.
Population III began with the formation of the first stars in the Universe, when the Universe was a few hundred million years old. These would be stars that could be tens to hundreds of times the mass of the Sun.
The Mystery of Population Stars III
Population III stars are expected to be giant, blue, very luminous stars. Indeed, the absence of metal in its composition would allow it to reach a fairly high size and luminosity..
However, as they are large luminous stars, the fuel quickly – caused by the fusion of the elements within them – would end and they would be stars with very short lives. They are expected to live only a few million years.
For this reason, these stars have never been observed in the Universe, after all, they ceased to exist a long time ago. Their lack of observation has left an open question in astronomy: did they really exist?
The discovery of the JWST
Using data from the James Webb Telescope, a Cambridge team may have found some of the earliest evidence of stars from this population. This happened after examining the spectrum of a region near one of the most distant galaxies ever discovered, GN-z11.
The GN-z11 galaxy already existed when the Universe was only 400 million years old, a time when some population III stars must have existed in the halo of galaxies.
The spectrum indicates the presence of a helium line which would only be possible in the presence of something that strongly ionizes this element. The idea is that the region was ionized by the presence of a Population III star with 500 times the mass of the Sun.
The end of a mystery?
It’s still too early to confirm whether we’ve reached the end of an answer to the decades-old question. One possibility raised by astronomers is that the region was ionized by Activity of a supermassive black hole and not a population III star.
The paper published by the group does not confirm that a population III star was finally detected, but this is the article with the best evidence and arguments for the possibility that we have found these stars.
It’s the second astronomical mystery to appear to receive light in a matter of weeks, both thanks to the superpowered James Webb Telescope.