Shady Abdel Hafez
In the field of astrophysics, researchers are interested in learning about the oldest stars in the universe, because it opens a wide door for them to study the properties of the early universe, and gives them signals to confirm or modify the models they use to determine the ages of stars.
History of the stars
Several months ago, a team led by researchers from the National University of Australia determined the age of a star called "SMSS J160540.18-144323", located 35,000 light-years from Earth. To reach these results, scientists examined the amount of iron in this star.
To understand this idea, we can start from the formation of stars, where hydrogen collects in the interstellar gas clouds and clumps until its center temperature reaches tens of millions of degrees Celsius, and here the interaction of nuclear fusion begins to occur.
Nuclear fusion means that hydrogen atoms combine to make helium, then after a future stage of the life of the star, helium converts to higher elements in the periodic table arrangement such as carbon and oxygen, and at the end of the ages of giant stars, iron is formed, and then is followed by a massive explosion that we know as the supernova (Supernova). .
As the star explodes, massive amounts of iron are released into space and enter the composition of new stars in small proportions. The sun, for example, contains 0.0030% of the iron in its atoms. This iron was not produced by the nuclear fusion of the sun, but rather is caused by the explosion of another former star.
According to this study, which was published in the monthly publications of the British Royal Society of Astronomy, the lower the iron levels in a star, the older it was, meaning that the first giant stars in the universe were formed from pure hydrogen, and after they exploded, they transferred some iron to the second generation of stars, which He in turn transferred a greater amount of iron when it exploded to the third generation, and so on.
The percentage of iron in “SMSS J160540.18–144323” is a billion and a half times that of the sun, and this indicates that it may be from the second or third generation of stars that formed during millions of years after the Big Bang.
Older than the age of the universe
But the models that astronomers use to track the ages of deep stars may be inaccurate, and one of the most important examples of this idea is a star called "HD 140283" in the constellation Libra. The researchers from the European Space Agency in 2000 estimated the age of this star at about 16 billion years.
These were shocking results for all astronomers of the world. We know that there is a lot of evidence to support the validity of the assumption that the age of the entire universe is 13.8 billion years, which means that the age of this star is greater than the age of the universe itself.
After that, a set of improvements appeared on mathematical models that measure the ages of stars. Researchers assumed from the agency that the quantities of helium in the nucleus of stars are greater than imagined, which may increase the speed of their nuclear fusion, so the age of the star decreases, and the research team has already reached an approximate age of " HD 140283 ″, but it's still about 14.4 billion years old, to increase or decrease 0.8 billion years.
Hence, until now, this problem continues to boggle physicists and cosmologists, but in return it creates questions that in turn open the door to a better development of the accuracy of the laws they use to explain this universe, and we may discover the secret of dark energy or matter someday thanks to such questions.