Scientists estimate the age of our universe at 13.8billion years. But when did the first stars appear? The answer was found out several years ago - according to the results of a study published in the journal Nature, the very first celestial bodies were lit 180 million years after the Big Bang. In fact, scientists still cannot say with certainty when exactly the first stars and galaxies were born, but there is every reason to believe that this happened 400-500 million years after the Big Bang - it was then that the Universe became cold enough to form neutral hydrogen molecules and their associations in giant clouds of gas, in which stars form. But could some stars form earlier, soon after the Big Bang?
How to determine the age of a star?
To begin with, the age of our universemanaged to be established only in 1929, after the American astronomer Edwin Hubble discovered that in addition to our galaxy, there are others in the vastness of the universe. Moreover, all these objects are removed from each other. Hubble realized that by dividing the distance between galaxies by the speed of their distance from each other, one can calculate how long they were at one point.
Of course, this is a rough estimate of the age of the universe. For greater accuracy, it is necessary to take into account that, due to the mutual attraction of the galaxy, they “slow down” somewhat, and the recently discovered dark energy, on the contrary, accelerates them. The latest estimate of the age of the universe - according to the Planck spacecraft, is 13.8 billion years. It was possible to establish this using the discovery of cosmic microwave background radiation or relic radiation.
Background radiation - This is thermal radiation that uniformly fills the universe. It is believed that it originated in the era of primary hydrogen recombination in the early Universe.
But how to determine the age of the stars? As the scientists explained, the iron content in the star is a good indicator of its age. It is important to understand that during the first two years of the universe stars consisted mainly of hydrogen and helium. However, in larger stars differentelements, such as silicon and iron, are formed as a result of nuclear fusion. Through this process, the atomic nuclei of lighter elements fuse together to create heavier ones.
This is interesting: Scientists kill stars in a computer simulation. But why?
As soon as a star becomes a supernova, an explosion spreads its elements throughout the Universe, turning them into building blocks of new star formations. Let me remind you that supernova flash - this is a phenomenon during which the brightness of a massive star increases by 4-8 orders of magnitude, after which a slow decay occurs.
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The oldest star in the Milky Way galaxy
According to the results of the study,published in Monthly Notices of the Royal Astronomical Society: Letters, researchers have been able to discover the oldest star in the universe. As the authors of the scientific work write, a group of astronomers observed a star that could well turn out to be almost as ancient as the Universe itself. According to scientists, the red giant, which will soon become a supernova, has the lowest iron level compared to other currently known stellar objects.
Extremely low iron content in the red giantled researchers to conclude that the star was born at a time when other stars in the universe did not contain as many elements as they are today. The authors of the article also draw attention to the fact that the star is at the last stage of its evolution - massive red giants, as a rule, end their lives as a supernova burst, after which they become either neutron stars (the densest objects in the Universe) or collapse into black holes. Space is a very mysterious place.
And what do you think, when the first stars appeared in the Universe? Let's talk about this with the participants in our Telegram chat, as well as in the comments to this article!
A star discovered by an international team of researchers has been identified as SMSS J160540. 18-144323.1. It is noteworthy that it is located withinThe Milky Way galaxy is located approximately 35,000 light-years from Earth. By observing a star, scientists discovered that it contains the lowest iron level of all known stars in the entire galaxy.
Thus, the discovery suggestsSMSS J160540.18-144323.1 belongs to an ancient group of stars whose life path can be traced back to the Big Bang - the main cosmic event that created the universe 13.8 billion years ago.
This incredibly anemic star thatprobably formed just a few hundred million years after the Big Bang, has an iron level of 1.5 million times lower than that of the Sun. It’s like one drop of water in the Olympic pool.
Lead author of the study Thomas Nordlander.
To summarize the results of the latterscientific research, then three things obviously become: firstly, the star SMSS J160540.18-144323.1 will soon use up all the fuel that feeds it and becomes a supernova; secondly, scientists cannot yet say exactly when the first stars appeared in the Universe. But it also means that future research will undoubtedly help find the answer to this question; and thirdly, the star SMSS J160540.18-144323.1 is the oldest in our own galaxy.