• ‘Stellar rotation’: Supercomputers expose the hidden mixing engine inside red giants New 3D simulations show rotation helps elements cross internal barriers in red giant stars. • Supercomputer simulations have helped astronomers solve a decades-old mystery about red giant stars. • Researchers say stellar rotation is the missing link explaining how chemical elements from deep inside these stars reach their surfaces as they age. • For years, scientists have struggled to understand how changes in chemical composition at the core of a red giant connect to shifts seen at the surface. • A stable internal layer acts as a barrier between the nuclear-burning core and the outer convective envelope. • How elements cross that barrier remained unclear.
Article Summaries:
- New 3D hydrodynamical simulations from the University of Victoria and the University of Minnesota show that rotation drives the mixing of chemical elements across the stable barrier between the core and envelope of red‑giant stars. The models, which run on large supercomputers, reveal that rotationally amplified internal gravity waves transport material far more efficiently than previously thought-over 100 times faster than in non‑rotating stars. This mechanism explains long‑observed surface abundance changes, such as altered carbon‑12 to carbon‑13 ratios, and provides a quantitative link between core nucleosynthesis and surface composition. The findings improve our understanding of stellar evolution and the future of Sun‑like stars.
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