A groundbreaking set of supercomputer simulations is offering a vivid glimpse into how the universe’s first stars, known as Population III stars, emerged from the chaos of the early cosmos.
These simulations, led by Ke-Jung Chen of the Institute of Astronomy and Astrophysics at Academia Sinica in Taiwan and detailed in a study published in The Astrophysical Journal Letters, reveal that violent turbulence in primordial gas clouds played a far more significant role in star formation than previously thought.
Unlocking The Dark Ages
The earliest era after the Big Bang, known as the Dark Ages, began about 370,000 years after the universe’s birth. The cosmos had cooled enough to become transparent, allowing light to travel freely, yet no stars had formed to illuminate it. This period ended a few hundred million years later, when the first stars ignited and transformed the cosmic landscape. Directly observing individual stars from over 13 billion years ago is impossible with current telescopes, but advanced simulations provide a powerful alternative.
Using the GIZMO simulation code and large-scale data from the IllustrisTNG Project, researchers recreated the conditions leading up to the birth of the first stars. By increasing IllustrisTNG’s resolution by a factor of about 100,000 through a technique called particle splitting, they were able to capture the movement of gas at unprecedented scales—down to fractions of a parsec.
Turbulence In Primordial Clouds
The simulation began with a dark matter mini-halo roughly 10 million times the mass of the Sun. Gas streamed into the mini-halo’s gravity at speeds five times faster than sound, creating supersonic turbulence. Instead of disrupting star formation, this turbulence caused the gas to fragment into multiple dense clumps, each with the potential to form stars.
One such clump reached the Jeans instability threshold, collapsing into what would become a star about 8 solar masses in size. According to the researchers, the gas accretion process was “highly anisotropic and inhomogeneous,” shaped by tidal forces from the assembling dark matter halo. This chaotic motion not only fostered clump formation but also influenced the size and distribution of the earliest stars.
First Stars Mystery Solved?
Astronomers have long debated whether Population III stars were massive solitary giants or more numerous smaller stars. Traditional models suggested masses ranging from 80 to 260 solar masses, with many ending their lives as pair-instability supernovae—explosions that leave distinct chemical signatures in later generations of stars. Yet, despite decades of searching, such signatures have not been conclusively found.
These new simulations offer a possible explanation. If the first stars were less massive and supernovae were rare, the absence of those chemical fingerprints in today’s oldest stars becomes easier to understand.
“This is the first time we’ve been able to resolve the full development of turbulence during the earliest phases of the first star formation,” Chen explained. “It shows that violent, chaotic motions were not only present—they were crucial in shaping the first stars.”
Bridging Cosmic Scales
By connecting large-scale cosmic structure formation with the small-scale processes that drive star birth, the team has taken a significant step toward understanding the cosmic dawn. The results suggest that turbulence generated during early structure formation may have naturally regulated the mass scale of Population III stars, reshaping theories about how the first light in the universe began to shine.
“These simulations represent a leap forward,” said Chen. “By uncovering the role of turbulence, we’re one step closer to understanding how the cosmic dawn began.”
Source link
