A new study concluded that the universe in its infancy knew only giant sizes of stars, due to the complex physics in the universe at that time, which may have led to the emergence of massive stars.
The new study concludes that the first stars in the universe exceeded 10,000 times the mass of the sun, nearly a thousand times more massive than the largest stars in existence today. Today, the largest stars reach only 100 solar masses.
“universetoday” states that astronomers have questioned over the years about the supposed size of the first stars, and some early estimates predicted that these stars could be hundreds of times larger than the mass of the sun, while later simulations suggested that they could be of the same size. Slightly larger than normal, but that wasn’t true according to the new study.
The researchers also found that these giant stars lived quickly and died very young. In general, the larger the star, the shorter its life, and once giant stars died, the conditions were not suitable for them to form again.
But why did that happen in the first place? And why are conditions no longer in place in the universe for such giant stars to be born again?
Why don’t giant stars form again?
According to the scientific “LiveScience” website, not long after the Big Bang, more than 13 billion years ago, when there were no stars in the universe in the first place, the universe contained only a warm mixture of natural gas that formed approximately entirely of hydrogen and helium.
Over hundreds of millions of years after that, in a period known as the cosmic dark ages, this neutral gas began to accumulate increasingly into balls of dense matter.
Usually, these balls of dense matter quickly collapse to form stars in our modern universe, but this did not happen in the cosmic dark ages, and the reason for this is because the universe now contains something that was lacking in the early universe, which is many elements heavier than hydrogen and helium, while The primitive era contained almost nothing but hydrogen and helium.
These heavier elements are very efficient at radiating energy away, allowing dense clumps to contract very quickly, and then collapse to densities high enough to trigger nuclear fusion, the process that powers stars by combining lighter elements into heavier ones.
These heavy elements were not available in the primordial universe because the only way to obtain these elements in the first place is through the process of nuclear fusion itself.
According to the NASA website, when extremely massive stars collapse on their way to death, the collapsing core becomes hot enough to support the most exotic nuclear reactions that consume helium and produce a variety of heavier elements, even iron.
This is what multiple generations of star formation, merging, and death have led to, enriching the universe to its current state and providing heavy materials that contribute to star formation after that. So, the first generation of stars formed under much different and more difficult conditions.
How do stars usually form?
Stars are born inside dust clouds that spread in most galaxies, and one example of dust clouds is the Orion Nebula, and deep disturbances within these clouds lead to the emergence of nodes of sufficient mass that gas and dust can begin to collapse under the influence of their gravity, so the nodes take a spherical shape And that huge ball of gas and dust remains in a contraction accompanied by a rise in the temperature of the gas.
Gas usually consists of hydrogen and helium, which are the lightest elements, and the gas temperature continues to rise due to contraction, so the atoms turn into ions and free electrons at high temperature, and that state is called plasma.
The plasma ball continues to contract under the action of its gravity, and its temperature increases until it is sufficient to start the reaction of the ionized hydrogen element to form the helium element. This interaction is called nuclear fusion, and it produces very large energy, so the star begins to shine.
As for the first stars, they were not just ordinary fusion factories. They were giant masses of neutral gas that ignite their fusion nuclei at once, skipping the stage in which they crumbled into small pieces, and then the resulting stellar mass was huge.
These first stars were very bright, and yet they lived a very short life, less than a million years. While stars in the modern universe can live billions of years, after that the giants of stars will die in supernova explosions.
To understand the mystery of these first stars, a team of astrophysicists turned to sophisticated computer simulations of the Dark Ages to understand what was happening back then.
The researchers found that a complex web of interactions preceded the formation of the first stars. Neutral gas, the gas that has the lowest and lowest degree of reactivity with other substances, began to clump together, and the hydrogen and helium gave off little heat, allowing the clumps of neutral gas to slowly reach a higher density.
But the higher-density clumps became very warm, producing radiation that separated the neutral gas from breaking up into many smaller clumps, meaning that the stars formed from these clumps could become gigantically large.