Some of the galaxy’s most spectacular stellar nurseries resemble giant cosmic wagon wheels, with spoke-like structures that scientists say were sculpted by shockwaves from stellar explosions and powerful stellar winds.
Using powerful 3D simulations, researchers from Kyushu University and Nagoya University in Japan found that shockwaves racing through giant clouds of gas can carve out the spoke-like filaments often seen surrounding newborn stars. The findings could help explain the origin of so-called hub-filament systems — sprawling star-forming regions where long streams of gas radiate toward a dense central hub, creating a pattern that resembles the spokes of a wheel, according to a statement from Kyushu University.
“Stars are born inside molecular clouds — vast, cold clouds of gas that drift through space,” Shingo Nozaki, lead author of the study, said in the statement. “But they only form in the coldest and densest parts of those stellar nurseries, where gas can collapse under its own gravity. In some of these star-forming regions, gas is organized into characteristic hub-and-spoke patterns known as Hub-Filament Systems (HFS).”
Astronomers have observed these structures throughout the Milky Way, but exactly how they form has remained an open question. The team used advanced 3D magnetohydrodynamic simulations to recreate the process, revealing that shockwaves propagating through giant molecular clouds can naturally generate the striking wheel-like architecture seen in some of the galaxy’s most active stellar nurseries, according to the study.
Many stellar nurseries contain narrow filaments that funnel material inward toward crowded central regions where stars are actively forming. Understanding how those filaments emerge is key to understanding how gas accumulates and ultimately collapses into new stars.
For the study, the researchers built a virtual molecular cloud threaded with magnetic fields and ran the simulations on ATERUI III, a supercomputer dedicated to astronomical research. Gravity first was seen pulling the magnetic fields inward, creating an hourglass-shaped configuration. The team then blasted the cloud with a simulated interstellar shockwave similar to those generated by expanding supernova remnants or powerful winds from massive stars. The result was a remarkably realistic hub-filament system.
As the shockwave swept through the cloud, it encountered different parts of the curved magnetic field at varying angles, creating oblique shocks that amplified sections of the field and established preferred pathways for gas to flow. Over time, these channels funneled material into elongated filaments stretching toward a central hub, producing the spoke-like structure seen in telescope observations.
The simulations also tracked how matter moves through stellar cradles. Dense gas tends to flow along the filaments, accelerating as it approaches the hub, while lower-density material between the spokes remains comparatively still. The researchers say this behavior may help explain why only a small fraction of gas in molecular clouds ultimately forms stars, according to the statement.
Modeling the interplay between gravity, magnetic fields and shockwaves over millions of years, allows researchers to study processes that are otherwise difficult to observe directly. Future work will test a broader range of cloud structures and shockwave conditions, which could clarify why hub-filament systems vary across the Milky Way and offer new insight into the formation of massive stars and stellar clusters. The results also point to a broader cosmic cycle of destruction and creation, in which shockwaves from dying stars help shape the environments where new stars are born.
Their findings were published March 18 in The Astrophysical Journal Letters.
