According to the sheet Space, today the greatest “giants” in the stellar world are only ten times as massive as our Sun. Those supermassive stars are extremely rare. But 13 billion years ago, their “ancestor” was completely different.
Astronomers have long known how stars today come to exist, surrounded by worlds as chemically rich as Earth’s: Over many generations stars die and are left behind. richer heritage for the next generation, just like how all species evolve.
Graphic image of the wild early universe with giant supernovas, glowing monster black holes… – Photo: ESA
To find out how the first stars were born, a team of scientists from Kyoto University’s Graduate School of Science and Tohoku University’s Graduate School of Science (Japan) used a computer simulation sophisticated way to “turn back” cosmic time.
They chose to explore the “dark age”, a few hundred million years after the Big Bang, when a generation of stars was born “out of nowhere”.
This computer model includes all the usual cosmic ingredients: Dark matter that helps grow galaxies, evolution and clumps of neutral gas, radiation that can cool or heat gas…
In addition, it has something especially important to the first stars: Cold, fast-moving streams of matter that crash into already-formed structures.
They found that a complex web existed before the first generation of stars: Neutral gas began to coalesce. The poor early universe consisted mainly of hydrogen and helium, but they were the ones that released the heat that helped these neutral gas masses reach higher and higher densities.
The conduction high-density clusters become very warm, generating radiation that disrupts the neutral gas and prevents it from fragmenting into many smaller clusters. Thus, the stars born from these clusters are extremely large, with a common size of about 10,000 times the Sun, or 1,000 times the largest stars today.
Those would be extremely bright and extremely short-lived stars, less than 1 million years. In a violent death in the form of supernovas much larger than today’s supernovas, these early “giants” began to pour out into the universe the products they produced from particle fusion. core – are elements heavier than hydrogen and helium.
This cycle repeats continuously throughout the universe and 13 billion years later, the universe possesses stars much smaller but contains an extremely rich chemical composition, including many heavier elements.
But also because the universe is full of heavy elements, the neutral gas clusters never get hot enough and coalesce large enough to create giant monsters.
The study has just been published online on the scientific database arXiv and is awaiting peer review Monthly Notices of the Royal Astronomical Society for official publication.
