Supercomputers just solved a 50-year-old mystery about giant stars

Science News from research organizations Supercomputers just solved a 50-year-old mystery about giant stars Spinning stars hold the secret to a long-unsolved red giant mystery. Date: March 24, 2026 Source: University of Victoria Summary: Astronomers have finally cracked a decades-old mystery about red giant stars—how material from their deep interiors makes its way to the surface. Using cutting-edge supercomputer simulations, researchers discovered that stellar rotation plays a powerful role in mixing elements across a previously unexplained barrier inside the star. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY Supercomputer simulations reveal that spinning stars mix their internal elements far more efficiently than previously thought. This discovery solves a decades-old puzzle about why red giants show unexpected chemical changes. Credit: AI/ScienceDaily.com Recent advances in supercomputing have allowed scientists to tackle a long-standing question in astronomy. Researchers have been trying to understand why the chemical makeup at the surface of red giant stars changes as these stars evolve. For many years, scientists struggled to connect what happens deep inside a red giant to what is observed at its surface. Nuclear reactions in the core alter the star's internal composition, but a stable layer separates this region from the outer convective envelope. How material manages to cross this barrier and reach the surface remained unclear. In a new study published in Nature Astronomy, researchers from the University of Victoria's (UVic) Astronomy Research Centre (ARC) and the University of Minnesota have now found the answer.

Stellar Rotation Drives Element Mixing The key factor is stellar rotation. "Using high-resolution 3D simulations, we were able to identify the impact that the rotation of these stars was having on the ability for elements to cross the barrier," says Simon Blouin, lead researcher and postdoctoral fellow at UVic. "Stellar rotation is crucial and provides a natural explanation for the observed chemical signatures in typical red giants. This discovery is another step forward in understanding how stars evolve." Scientists have long known that stars like our Sun expand dramatically once they run out of hydrogen in their cores, becoming red giants that can grow up to 100 times their original size. Since the 1970s, astronomers have detected changes in their surface chemistry during this phase, including shifts in carbon-12 to carbon-13 ratios. These changes suggest that material from deep inside the star must be transported outward, but the exact mechanism had not been confirmed. "We knew that internal waves, generated by churning motions in the convective envelope, were able to pass through this barrier layer, but previous simulations found that these waves transported very little material. We were able to show that the rotation of the star dramatically amplifies how effectively these waves can mix material across the barrier, to an extent that matches the observed changes in surface composition," explained Blouin. Blouin and his colleagues found that rotation can boost mixing rates by more than 100 times compared to stars that are not rotating. Faster rotation leads to even stronger mixing. Because our Sun will eventually become a red giant, these findings also provide insight into its future evolution.

Advanced Simulations Reveal Hidden Processes To uncover this process, the team relied on hydrodynamical simulations, which model how material flows inside stars in three dimensions. These simulations are extremely complex and require powerful computing systems, making the discovery possible only with recent advances in supercomputing. "Until recently, while stellar rotation was thought to be part of solving this conundrum, limited computing abilities prevented us from quantitatively testing the hypothesis," says Falk Herwig, principal investigator and director of ARC. "These simulations allow us to tease out small effects to determine what actually happens, helping us to understand our observations." The researchers used computing resources from the Texas Advanced Computing Centre at the University of Texas at Austin and the Trillium supercomputing cluster at SciNet at the University of Toronto. Trillium, launched in August 2025, is among the most powerful systems available in Canada for large-scale academic simulations and is part of the Digital Research Alliance of Canada. Its enhanced processing capabilities played a crucial role in enabling this work. "We were able to discover a new stellar mixing process only because of the immense computing power of the new Trillium machine. These are the computationally most intensive stellar convection and internal gravity wave simulations performed to date, " said Herwig. Broader Impact and Future Research The methods used in this study extend beyond astrophysics. The same computational approaches can help scientists better understand fluid motion in many systems, including ocean currents, atmospheric patterns, and blood flow. Herwig is collaborating with researchers in these areas to build shared tools and infrastructure for large-scale simulations. Blouin plans to continue exploring how stellar rotation affects different types of stars. Future work will examine how varying rotation patterns influence mixing efficiency and whether similar processes occur in other stages of stellar evolution.

This research was supported by the Natural Sciences and Engineering Research Council (NSERC), the National Science Foundation (NSF) and the US Department of Energy. RELATED TOPICS Space & Time Stars Astrophysics Space Telescopes Space Exploration Matter & Energy Chemistry Energy and Resources Physics Inorganic Chemistry RELATED TERMS Astronomy Interstellar medium Star Trek Extrasolar planet Supernova Uranus' natural satellites Open cluster Nanoparticle Story Source: Materials provided by University of Victoria. Note: Content may be edited for style and length. Journal Reference: Simon Blouin, Paul R. Woodward, Pavel A. Denissenkov, Praneet Pathak, Falk Herwig. Wave-driven mixing enhanced by rotation in red giant branch stars. Nature Astronomy, 2025; 10 (3): 385 DOI: 10.1038/s41550-025-02743-z Cite This Page: MLA APA Chicago University of Victoria. "Supercomputers just solved a 50-year-old mystery about giant stars." ScienceDaily. ScienceDaily, 24 March 2026. . University of Victoria. (2026, March 24). Supercomputers just solved a 50-year-old mystery about giant stars. ScienceDaily. Retrieved March 24, 2026 from www.sciencedaily.com/releases/2026/03/260324024300.htm University of Victoria. "Supercomputers just solved a 50-year-old mystery about giant stars." ScienceDaily. www.sciencedaily.com/releases/2026/03/260324024300.htm (accessed March 24, 2026). Explore More from ScienceDaily RELATED STORIES Astronomers Discover Stars Don’t Spread Life’s Ingredients the Way We Thought Jan. 12, 2026 — Scientists observing the red giant star R Doradus have found that starlight isn’t strong enough to drive its stellar winds, overturning a long-standing theory. The dust grains around the star are ...

Dwarf Galaxies Use 10-Million-Year Quiet Period to Churn out Stars Nov. 21, 2023 — If you look at massive galaxies teeming with stars, you might be forgiven in thinking they are star factories, churning out brilliant balls of gas. But actually, less evolved dwarf galaxies have ...

Hubble Finds Spiraling Stars, Providing Window Into Early Universe Sep. 8, 2022 — Stars are the machines that sculpt the universe, yet scientists don't fully know how they form. To understand the frenzied 'baby boom' of star birth that occurred early in the ...

Mixing Things Up: Optimizing Fluid Mixing With Machine Learning Aug. 29, 2022 — Fluid mixing is an important part of several industrial processes and chemical reactions. However, the process often relies on trial-and-error-based experiments instead of mathematical optimization. ...

Where Does Gold Come From?

New Insights Into Element Synthesis in the Universe Nov. 15, 2021 — How are chemical elements produced in our Universe? Where do heavy elements like gold and uranium come from? Using computer simulations, a research team shows that the synthesis of heavy elements is ... Surprise: The Milky Way Is Not Homogeneous Sep. 8, 2021 — In order to better understand the history and evolution of the Milky Way, astronomers are studying the composition of the gases and metals that make up an important part of our galaxy. Three main ... TRENDING AT SCITECHDAILY.com Revolutionary Submarine Mysteriously Disappears Without a Trace – Scientists Are Now Preparing for a Bold Return Scientists Discover a Better Way To Reduce Dangerous Belly Fat in Older Women New Study Reveals Surprising Effect of Drinking Coffee at Night The Surprising Reason Balance Gets Worse With Age and Parkinson’s