Astronomers analysed Gemini data on a very distant quasar and discovered chemical residues that might have belonged to one of the first stars to shine the universe.
A group of researchers from the University of Tokyo worked on the analysis of a distant quasar, observed by the 8.1-metre Gemini North telescope in Hawaii, managed by NOIRLab and part of the Gemini Observatory. During the study, scientists discovered an unusual proportion of the chemical elements that they assumed came from the explosion of one of the stars in the early universe. The mass of this first-generation star should have been about 300 times the mass of our Sun.
This discovery, which has yet to be confirmed, can shed light on everything we still do not know about the early universe. If the mysterious material discovered by scientists is the chemical remains of a star as ancient as the universe, it will be a huge breakthrough after decades of research, speculation and lack of direct evidence.
The first stars were probably formed when the universe was only 100 million years old, less than 1% of its current age, known as population III, or first-generation stars, these stars were so massive that at the end of their lives as supernovas, they were completely torn apart, clogging the interstellar space with a characteristic mixture of heavy elements.
Using an innovative method to determine the chemical elements contained in the clouds surrounding the quasar being studied, scientists noticed a very unusual composition: the material contained 10 times more iron than magnesium compared to the ratio of these elements in our sun.
Scientists believe that the most likely explanation for this characteristic is that the material was left behind by a first-generation star that exploded like a Supernova with unstable cores, which are extremely powerful versions of supernova explosions that have never been seen, but are assumed to be the end of the lives of giant stars with a mass of 150 to 250 times the mass of the Sun.
Supernova feeds interstellar space
Explosion of supernovas with steam instability occurs when photons in the center of the star spontaneously turn into electrons and positrons. This transformation reduces the radiation pressure inside the star, allowing gravity to overcome it and cause collapse and subsequent explosion. Such an event is so catastrophic that it is also called super super-supernova.
Unlike other supernovas, these events do not leave a star's residue, such as a neutron star or a black hole, but throw all the material into the environment. There are only two ways to find evidence of this:
- Seal a supernova with steam instability at the very moment it occurs. Identify a chemical signature supersupernova in a material thrown into interstellar space.
For their research, astronomers used the data of a spectrograph of the short-range infrared "Gemi" . Although it provides information on the constituent elements of the chemical elements, the electromagnetic spectrum does not allow for easy extraction of the content of each element. The brightness of the spectral line in fact depends on many factors, not just the number of elements in the chemical composition of the object being studied.
Innovative method for determining the chemical composition of stars
The search for chemical evidence of the existence of an earlier generation of high-mass stars in the III population has already taken place in the past among the stars of the Milky Way halo. In 2014, at least one preliminary identification was provided. Yuzuru Yoshia and Hiroaki Sameshima of the University of Tokyo and their colleagues, however, believe that the new result is the clearest sign of supernova with steam instability based on the extremely low ratio of magnesium abundance to the iron presented in this quasar.
In fact, they solved this problem by developing a method that uses wave lengths in the quasar spectrum to estimate the abundance of the elements present, using this method to analyse the quasar spectrum, they and their colleagues found a significantly low ratio of magnesium to iron.
The chemical signatures of the primal stars are even closer to us.
Researchers at the University of Tokyo believe that the chemical signatures of the ancient stars destroyed by the supernovas can be found even closer to us. Although the high mass stars of population III have been extinct for a long time, the chemical signatures that they leave in the discarded material can continue to exist for much longer and to this day, which means that astronomers can find the signatures of the explosions of supernovae long-dead stars still captured in the objects of our local universe.
In order to verify this interpretation more thoroughly, many more observations are needed to determine whether other objects display similar characteristics, but now that a person knows what to look for, he knows the path to be followed, in particular where and how to find evidence to solve one of the greatest secrets of the early universe.