For decades, astronomers have searched for the home of globular clusters, the dense spherical collections of stars that orbit galaxies today. These ancient systems are among the oldest visible structures in the universe, yet their early history remains difficult to reconstruct.
Most theories focused on crowded regions within young galaxies, where gas was abundant and star formation was intense.However, a new study published in the Astrophysical Journal of Galactics, titled “Too shy to spin? Cosmic upholstery flowers as elementary spherical clusters,” suggests interest elsewhere. Instead of forming deep within galactic disks, some of the first compact star clusters may have emerged in a relatively quiet region surrounding young galaxies. These neglected environments, sometimes described as perigalactic regions, contain streams of gas that feed growing galaxies.
According to simulations of conditions more than 13 billion years ago, these outskirts may have provided the right ingredients for the formation of extremely dense star clusters that bear a striking resemblance to objects recently observed by the James Webb Space Telescope (JWST).
how Gas filaments in Early universe Compact constellations were created
The study used high-resolution cosmological simulations to explore how star clusters appeared when the universe was still very young. The team examined galaxies spanning a wide range of masses at redshifts greater than seven, which corresponds to a period of less than a billion years after the Big Bang.
Within the simulations, they identified dozens of compact star systems forming outside the main galactic disks but still within the gravitational radius of their host dark matter halos. These clusters were not associated with the crowded central regions often associated with strong star formation. Instead, they appeared along the dense filaments of gas surrounding galaxies.The gas flowing through these filaments sometimes became unstable.
Under the right conditions, parts of the stream quickly fragmented and collapsed, producing compact concentrations of stars. What emerged were isolated clusters with remarkably high stellar densities, despite their distance from the central galaxy.
Compact star clusters have been detected by JWST mirror simulation results
Interest in these objects has grown in part because the James Webb Space Telescope (JWST) has begun detecting extremely compact star-forming systems in the distant universe.
Some of the most interesting examples have been seen through gravitational lensing, where the gravity of foreground galaxies inflates distant objects.According to Harvard University, the simulated clusters reached stellar surface densities similar to those inferred from compact clusters observed in the Cosmic Gemstone Arc, a system seen at a redshift of about 9.6. Although simulations cannot prove that the observed clusters formed by the same process, the similarities suggest that the environments surrounding galaxies deserve greater attention.This discovery expands the picture of where early star formation can occur. Young galaxies were not isolated islands. They are nestled within networks of gas filaments stretching across the cosmic web, and these structures may have hosted star formation themselves.
How did isolated star clusters become globular clusters?
Globular clusters are found around many galaxies today, including the Milky Way. They contain hundreds of thousands, and sometimes millions, of stars packed into relatively small volumes.
Many of them formed so early that they preserve clues about conditions in the nascent universe.The new work raises the possibility that at least some globular clusters did not originate within galactic disks at all. Instead, they may have begun their lives as isolated compact systems on the outskirts of galaxy formation before surviving for billions of years.If proven true, this image could help explain many ancient mysteries. Clusters that form outside crowded galactic environments may have followed different evolutionary paths, experienced fewer destructive encounters and retained distinct chemical signatures. Their unusual birthplace could still be reflected in the characteristics observed by astronomers today.This idea does not replace current formation scenarios, but it adds another route by which ancient globular clusters may have emerged.
