Scientists have discovered remains of suspected first generation stars.
The artist depicts the "third type of stars". This type of star only existed about 100 million years after the creation of the universe. NOIRLab / NSF / AURA / J. da Silva / Spaceengine
There was a strange giant celestial body in the ancient universe. These celestial bodies can have a mass of more than 300 times that of the sun. They look like giant ordinary stars, which can glow and heat, but their operating mechanisms are different. These superstars are called "Population III stars".
"The Third Class Star" is considered by scientists to be the first generation of stars in the universe. They existed only 100 million years after the birth of the universe. Today, the "third type of stars" are no longer seen in the universe because they have all died long ago. And the way they die is through an unimaginable violent explosion. This type of explosion is called a "supernova". Although it is also named supernova , the severity, explosion mechanism and explosion legacy of the "super supernova" explosion are very different from ordinary supernova.
A "supernova" formed by an explosion of a star with a mass of 300 times the sun (imaginary image). NOIRLab / NSF / AURA / J. da Silva / Spaceengine
"Super Supernova" like ordinary supernova can provide the soil for future generations to nurturing. They will also spread a large number of heavy elements created by the kernel into the universe. For a new generation of stars, planets and even us to be born in such an environment.
Like many legends originating from ancient times, it is difficult for us to find these theoretical "third-class stars" in today's universe, even if it is a little clue left by them.
But difficulty does not mean impossible.
Recently, some astronomers used the North Heaven Gemini telescope to study an extremely distant quasar . Quasar is essentially a galaxy, but there is an active supermassive black hole in the center, aiming at the earth with its energy beam released from its swallowing matter, so it looks abnormally bright.
This quasar exists in space and time about 13.1 billion light years ago, which means that it exists only 700 million years after the creation of the universe. By analyzing the spectrum of light transmitted to the earth by this quasar, astronomers discovered that around the quasar, there is a special interstellar cloud cluster in the universe between it and the earth, and the chemical characteristics of this cloud cluster are very special.
Researchers found that the proportion of iron and magnesium in chemical elements in the cloud is abnormally high, 10 times higher than that of the sun. Based on this, this cloud cluster is the remains of the first generation of stars in the universe, that is, the "third type of stars". This "third star" with a mass of 300 times the sun suffered a big explosion at the moment of death, becoming a "pair-instability" supernova called .
is different from ordinary supernovae that causes the outer layer to collapse and cause rebound explosion, the explosion of "op-instability" supernovae is caused by the decay of photon inside the star. When the photons inside the star begin to decay into pairs of electrons and positrons and , the thermal pressure inside the star weakens, local collapses, and then the overall loss of balance and burns rapidly, causing a thermonuclear explosion.
Ordinary supernova explosion will always leave a dense kernel, whether it is neutron star or black hole; and this type of supernova will not leave anything behind. All the wreckage was thrown into space and became a spreading cloud.
This special way of death of "the third type of stars" means that we have no way to find the core remains of such stars in the universe today. Therefore, there are only two ways to verify this prediction: directly observe the "super supernova", or look for the chemical characteristics left by the "super supernova" in the interstellar medium . The former is basically impossible.
researchers believe they found the most clear evidence to date related to "third class stars" and "pair-instability" supernova.
Compared with directly observing "third-class stars", it is easier to observe the chemical characteristics left by "op-instability" supernova. These features may remain in the universe for a long time and can therefore be found in space closer to Earth.
quasar diagram. NOIRLab / NSF / AURA / J. da Silva / Spaceengine
Reference
Potential First Traces of the Universe’s Earliest Stars
https://noirlab.edu/public/news/noirlab2222/
Potential signature of Population III pair-instability supernova ejecta in the BLR gas of the most distant quasar at z = 7.54
https://arxiv.org/abs/2207.11909
