Supercomputer Reveals How Exploding Stars “Stir” the Galaxy from the Bottom Up

citaadmin — Mon, 01 Jun 2026 21:28:45 +0000

Supercomputer Reveals How Exploding Stars "Stir" the Galaxy from the Bottom Up

June 1, 2026

Caption (works for any): the explosions of dead stars extracted from a simulation of a galactic disk. The most intense colors indicate where the turbulence in the explosions is being generated from, which traces an unstable thin shell around the dead stars.

New research performed on the at the University of Toronto reveals a fundamentally different mechanism by which exploding stars shape the turbulent structure of our galaxy. The study, authored by , postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics (CITA), was accepted for publication in . It challenges long-standing assumptions about how turbulence is generated and sustained in the interstellar medium.

Turbulence—the chaotic, swirling motion of gas—is a fundamental process in astrophysics, influencing everything from star formation to the transport of energy and magnetic fields across galaxies. For decades, scientists have largely assumed that turbulence in the Milky Way follows a classical cascade: energy injected at large scales breaks down into progressively smaller eddies (vortices or “swirls”), consistent with the well-known Kolmogorov picture.

However, this new work demonstrates that supernova remnants—the expanding shells of gas left behind by stellar explosions—can instead inject turbulence at small scales that, then, propagates upward to larger scales through an inverse cascade. This finding suggests that the dominant source of galactic turbulence may not operate in the way previously thought. Instead of a top-down energy transference (dying out of energy), it’s a bottom-up build-up. His research shows that supernova explosions create microscopic, chaotic swirls first. Those tiny swirls then merge and push their energy upward, eventually creating the massive, large-scale turbulence that shapes our entire galaxy.

“Our results show that the structure of turbulence in the galaxy carries a direct imprint of the physical instabilities that occur in supernova remnants,” said Dr. Beattie. “Rather than simply decaying or cascading downward, turbulence generated at the interfaces within these remnants can grow and reorganize, ultimately influencing dynamics on galactic scales.”

The research identifies the contact discontinuity—the unstable boundary between hot, shocked ejecta and cooler surrounding gas—as a key site of turbulence generation. Instabilities and strong baroclinic effects at this interface drive the formation of vortical motions that seed turbulence at relatively small spatial scales. From there, nonlinear interactions transfer energy to larger scales, producing a turbulent spectrum that deviates significantly from classical expectations.

Crucially, these results were made possible by cutting-edge numerical simulations performed on the Trillium Supercomputer, one of Canada’s most advanced high-performance computing systems operated by SciNet at the University of Toronto. The scale and fidelity required to resolve both the small-scale instabilities and their large-scale consequences demand computational resources at the forefront of modern supercomputing.

This revised picture has broad implications. It provides a new framework for interpreting observations of interstellar turbulence, including velocity fluctuations and magnetic field structure, and may help explain why measured spectra in the Milky Way often differ from theoretical predictions. It also suggests that models of galaxy evolution and star formation may need to be re-evaluated to account for this alternative turbulent driving mechanism.

Beyond its implications for the Milky Way, the work points to a more general principle: that microscopic plasma processes and instabilities can leave lasting imprints on macroscopic astrophysical systems.

“This is a shift in perspective,” Dr. Beattie added. “If turbulence in galaxies is seeded at small scales by physical instabilities, then understanding those instabilities becomes essential for understanding the large-scale universe.”

The paper is available on arXiv:

Beattie, J. 2026,��American Astronomical Society,��,��,��,��Supernovae Drive Large-scale, Incompressible Turbulence through Small-scale Instabilities.

SCIENCE CONTACT: Dr. James Beattie

Media Contact:
Lyuba Encheva, Communications and Events Coordinator
Canadian Institute for Theoretical Astrophysics, University of Toronto
Email: communication@cita.utoronto.ca

CITA Fellow James Beattie and his team use supercomputer simulations to challenge classical understanding of magnetic turbulence

citaadmin — Tue, 13 May 2025 12:08:09 +0000

Astronomers have developed a computer simulation to explore, in unprecedented detail, magnetism and turbulence in the interstellar medium (ISM)—the vast ocean of gas and charged particles that lies between stars in the Milky Way galaxy.

Turbulence is a ubiquitous phenomenon, which all of us have witnessed. The swirly movement of mixing milk in a coffee cup is the same in principle as the chaotic flows in the oceans, solar wind, interstellar medium (ISM) and plasma between galaxies. The key distinction in astrophysical environments is the presence of magnetic fields, which fundamentally alter the nature of turbulent flows. Magnetised turbulence, which is hard to capture through mathematical equations and computer models, is also believed to be a decisive factor in the distribution of particles in the universe, the density variations in gasses, ISM, and star formation.

A composite image of the Phantom Galaxy and (inset) a high-resolution simulation of galactic turbulence with magnetic field lines in white. Credit: ESA/Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team; Acknowledgement: J. Schmidt; Simulation: J. Beattie.

Using extremely high-resolution simulations of magnetized turbulence, CITA and Princeton Fellow James Beattie and his team show that the turbulent dynamics typical of the interstellar medium (ISM) significantly deviate from widely used classical models. The groundbreaking computer simulation the scholars have developed is described in , the model is the most powerful to date, requiring the computing capability of the SuperMUC-NG supercomputer at the Leibniz Supercomputing Centre in Germany. It directly challenges our understanding of how magnetized turbulence operates in astrophysical environments.

James Beattie, the paper’s lead author, is hopeful the model will provide new insights into the ISM, the magnetism of the Milky Way Galaxy as whole, and astrophysical phenomenon such as star formation and the propagation of cosmic rays.

“This is the first time we can study these phenomena at this level of precision and at these different scales,” Beattie says.

Fractal density structures in the world’s largest turbulence simulation, with high-densities shown in red, and low-densities shown in blue. Credit: Simulation: J. Beattie.

The paper was co-authored with researchers from Princeton University; Australian National University; the Australian Research Council Center of Excellence in All Sky Astrophysics; Universität Heidelberg; the Center for Astrophysics, Harvard & Smithsonian; Harvard University; and the Bavarian Academy of Sciences and Humanities.

Turbulence – Canadian Institute for Theoretical Astrophysics

Supercomputer Reveals How Exploding Stars “Stir” the Galaxy from the Bottom Up