As the primary sources of heavy elements and ultraviolet radiation in galaxies, stars more than eight times the mass of the Sun play a dominant role in shaping galactic structure and evolution. Yet the mechanism that governs the formation of such massive stars in protoclusters has puzzled astronomers for decades.
An international team of astronomers led by Junhao Liu, Assistant Professor at Nanjing University, has discovered that turbulent compression, rather than magnetized collapse, is the primary mechanism shaping the seeds of massive star clusters. The findings overturn the classic picture of magnetically regulated star formation and offer a new explanation for how the universe’s most influential stars acquire their mass. The research is published in a paper titled “The dominance of turbulence over magnetism in the formation of massive star cluster seeds” in Nature Astronomy on May 22, 2026.
Figure: An example ALMA image showing the magnetic field orientation and 1.3 mm dust continuum of a massive star formation region from the survey.
The team conducted the largest survey of magnetic fields in high-mass star-forming regions using the Atacama Large Millimeter/submillimeter Array (ALMA). By observing 30 massive star-forming regions in the Milky Way, the team for the first time obtained statistical evidence that at the small scales (~0.01 pc) where individual stars begin to form, the dense gas condensations (the “seeds” of massive stars) align parallel to the local magnetic fields. The team’s numerical simulations suggest that this parallel alignment is a distinct signature of supersonic turbulence dominating the dynamics of the gas, effectively scrambling the orderly influence of magnetism. This works also reveals a possibly turbulence-induced misalignment between magnetic fields and rotation, which allows massive protostellar disks to survive and feed the growing stars.
“Magnetic fields or turbulence? It is a cosmic battle between order and chaos. While orderly magnetic fields clearly structure giant molecular clouds and clumps on large scales, our results show they lose the battle against chaotic turbulence when it comes to forming individual stars and clusters,” said Junhao Liu, lead author of the paper. “This discovery shifts our understanding of massive star cluster formation from a magnetically regulated, orderly process to one driven by cosmic chaos. I expect this study not only solves an observational puzzle but will also stimulate future theoretical and simulation work to understand the detailed physical processes that form and feed these stellar seeds.”
“This work challenges classical magnetically-regulated star formation models,” said Patricio Sanhueza, Associate Professor at the University of Tokyo and Principal Investigator of the ALMA survey. “What is particularly exciting is that the small-scale behaviors of magnetic fields and turbulence are distinctly different from those observed on larger scales.”
This work involved 35 researchers from 29 institutions worldwide. The core institution is Nanjing University. Partner institutes include National Astronomical Observatory of Japan, the University of Tokyo, Academia Sinica, Center for Astrophysics | Harvard & Smithsonian, and others.
Article link：https://www.nature.com/articles/s41550-026-02873-y
arXiv link：https://arxiv.org/abs/2603.17254