The first stars in the universe may have risen above 10,000 times its mass the sunAbout 1,000 times larger than the largest stars alive today, a new study has found.
Today, the largest stars are 100 solar masses. But the early universe was a much more exotic place, filled with mega-giant stars that lived quickly and died very young, the researchers found.
And once these ruined giants died, the conditions were never right for them to form again.
Related: Our Expanding Universe: Age, History and Other Facts
Cosmic Dark Ages
13 billion years ago, not too long ago the big bang, the universe had no stars. There was nothing but a warm soup of neutral gas, almost entirely made up of hydrogen and helium. Over hundreds of millions of years, however, that neutral gas began to pile up into increasingly dense balls of matter. This period is known as the Cosmic Dark Ages.
In the modern-day universe, dense balls of matter rapidly collapse to form stars. But that’s because the modern universe has something the early universe lacked: elements much heavier than hydrogen and helium. These materials are very efficient at radiating energy away. This allows dense clumps to shrink very quickly, collapsing at concentrations high enough to trigger. Central addition – The process that combines lighter elements with heavier elements to make stars stronger.
But the only way to get heavy elements in the first place is through that same nuclear fusion process. Multiple generations of star formation, fusion, and death have enriched the universe to its present state.
Without the ability to rapidly release heat, the first generation of stars had to form under much different, and much more difficult, conditions.
To understand the puzzle of this first star, a team of astrophysicists turned to sophisticated computer simulations of the Dark Ages to understand what was happening back then. They reported their findings in a paper in January Published in the preprint database arXiv (opens in new tab) and submitted for peer review to the Monthly Notices of the Royal Astronomical Society.
The new work has all the usual cosmological ingredients: dark matter to help galaxies grow, evolution and coagulation of neutral gas, and radiation that can sometimes cool the gas and sometimes reheat it. But their work includes something others lack: cold fronts — fast-moving streams of cold material — that slam into already formed structures.
Researchers have found that a complex web of interactions precedes the formation of the first star. Neutral gases begin to collect together. Hydrogen and helium release heat little by little, allowing clumps of neutral gas to gradually reach higher densities.
But high-density clumps become very hot, producing radiation that dissociates the neutral gas and prevents it from splitting into many smaller clumps. That means stars formed from these clusters can be incredibly large.
This back-and-forth interaction between radiation and neutral gas led to the formation of huge pools of neutral gas—the beginnings of the first galaxies. Gas deep in these proto-galaxies forms rapidly rotating accretion disks – fast-flowing rings of material that form around massive objects, including black hole In the modern universe.
Meanwhile, at the outer edge of the proto-galaxy, a cold front of gas rained down. The coldest, most massive fronts entrained the proto-galaxies to the accretion disc.
These cold fronts hit the discs, rapidly increasing both their mass and density to a critical threshold, allowing the first stars to appear.
These first stars were not just any ordinary fusion factories. They were huge clumps of neutral gas that ignited their fusion cores all at once, skipping the stage where they break up into smaller pieces. As a result the stellar mass was huge.
These first stars were incredibly bright and short-lived, less than a million years. (Stars in the modern universe can live for billions of years). After that, they would have died in a supernova explosion.
These explosions carried the products of internal fusion reactions – elements heavier than hydrogen and helium – which then seeded the next round of star formation. But now contaminated by heavier elements, the process cannot repeat itself and those monsters will never appear on the cosmic scene again.
Originally published on LiveScience.com.
follow us @space.com (opens in new tab)or on Facebook (opens in new tab) And Instagram (opens in new tab).