What was the mass of the first stars?

The first stars that broke out in the universe were big. According to their mass, there is disagreement between observations and theory. Recently, scientists have used a supercomputer to sort them out.

Turbulence could have made the first stars smaller than previously thought. Source: phys.org

First stars

One of the most interesting tasks of modern astrophysics is to estimate the mass of the luminaries that existed at the very beginning of the universe. Back then, only hydrogen and helium were present, so the stars of the first generation, or, known as Population III, had to be very large. And in a new study, scientists have established exactly how much.

We cannot observe the stars of the first generation by themselves. They exploded before the Earth was even born. However, some of them became supernovae and generated a lot of heavy elements. And we still see them in some old stars. By estimating their number, scientists can determine the type of the first supernovae, and therefore the mass of the stars that produced them.

The only problem is that in this way scientists have estimated the average weight of the first stars from 12 to 60 solar masses. At the same time, theoretical constructions based on general phenomena about the early Universe gave an estimate of 50 to 1000 solar masses. That is much more.

Scientists do not know why there is such a discrepancy between theoretical predictions and observations. The debate about this has been going on for ten years. However, it is possible that a new study will finally put an end to them.

Simulation on a supercomputer

Scientists used a powerful supercomputer at the Berkeley National Laboratory in their work. With its help, they created the world’s first high-resolution three-dimensional hydrodynamic simulations of turbulent gas clouds in which the first stars were born.

It was turbulence, the occurrence of inhomogeneities in the movement of gas, that became the key to correctly estimating the mass of the first stars. Its existence has been confirmed by previous studies, and new modeling has shown that it is really important. After all, as a result of it, fragmentation of primary clouds occurs.

Scientists have found that the effect of turbulence leads to the fact that in the early Universe, clouds were torn into fragments weighing from 22 to 175 solar masses. And already stars 8-58 times more massive than the Sun were formed from them.

Thus, the new study has finally produced a theoretical result that is in good agreement with observations. It seems that the solution to the problem bothering scientists for 10 years really was that they did not take turbulence into account. 

According to phys.org

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