A new study has found that the first stars in space may have reached 10,000 times their mass. The Sun, which is about 1000 times more massive than the largest existing stars. Today, the largest stars have 100 solar masses. But the researchers found that the early universe was a much more exotic place, full of mega-giant stars that lived fast and died very, very young. And as soon as these doomed giants died, the conditions for their regeneration were no longer created.
More than 13 billion years ago, shortly after Big BangThere were no stars in the universe. It was nothing but a warm soup of neutral gas made almost entirely of hydrogen and helium. However, over hundreds of millions of years, this neutral gas began to accumulate into increasingly dense balls of matter. This period is known as the cosmic dark ages.
In the modern universe, balls of dense matter rapidly collapse to form stars. But that’s because the modern universe has what the early universe lacked: hydrogen and many elements heavier than helium. These elements dissipate energy very efficiently. This allows dense clumps to shrink very quickly and collapse to a high enough density to begin with. nuclear fusion It is the process that fuels stars by fusing lighter elements with heavier elements.
Cosmic Dark Ages
But the only way to get heavier elements is through the same nuclear fusion process. Several generations of stars that formed, merged, and died enriched the cosmos to what it is today. Incapable of rapidly releasing heat, first-generation stars had to form under much different and much more complex conditions.
To understand the riddle of these early stars, a team of astrophysicists turned to advanced computer simulations of the dark ages to understand what was going on back then. They reported their findings in a newspaper in January, Published in the arXiv preprint database and submitted for review to the Monthly Notices of the Royal Astronomical Society.
The new paper presents all the usual cosmological components: dark matter that fuels the growth of galaxies, the evolution and clustering of neutral gas, and radiation that can cool and sometimes heat gas. But their work has something that others lack: cold fronts – fast-flowing streams of chilled matter hitting preformed structures.
The researchers found that a complex web of interactions preceded the formation of the first star. Neutral gas began to collect and stick together. Hydrogen and helium gave off some heat, allowing the neutral gas clumps to slowly condense. But the high-density clumps got very hot, producing radiation that broke up the neutral gas and prevented it from splitting into many smaller clumps. This means that stars formed from these clusters can grow incredibly large.
These feedback interactions between radiation and neutral gas led to large pools of neutral gas that were the beginnings of the first galaxies. Gas deep within these protogalaxies formed rapidly spinning accretion disks—rings of fast-moving matter that form around large objects. black holes in the modern universe. Meanwhile, a cold gas front fell on the outer edges of the protogalax. The coldest, largest fronts penetrated the protogalaxies up to the accretion disk.
These cold fronts slammed into the disks and rapidly increased their mass and density to a critical threshold that allowed the first stars to appear. Those early stars were no ordinary fusion factories. They were huge clumps of neutral gas that instantly ignited fusion cores, bypassing the stage where they split into small pieces. The resulting stellar mass was very large.
These early stars would have been incredibly bright and extremely short-lived, less than a million years old. (Stars in the modern universe can live for billions of years). After that, they would die in violent supernova explosions. These explosions will carry the products of internal fusion reactions (elements heavier than hydrogen and helium), which will ignite the next round of star formation. But now, as they were infected with heavier elements, the process could not be repeated and these monsters would never appear on the cosmic stage again.
Source: Port Altele
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