Scientists have developed a groundbreaking method to measure solar radiation opacity under extreme conditions using helioseismology. The innovative approach, published in Nature Communications, not only highlights gaps in our understanding of atomic physics but also confirms recent experimental findings. These advances bring exciting new possibilities for astrophysics and nuclear physics.
Probing the sun's interior using sound waves
Helioseismology is the study of the sun's sonic oscillations, which allows scientists to explore the interior structure of stars with great precision. By analyzing these sound waves, researchers can determine key properties of the solar plasma, including its density, temperature and chemical composition. These insights are critical to understanding how the Sun operates and evolves over time. This approach essentially turns the Sun into a natural astrophysics laboratory, providing important data for refining stellar models and deepening our understanding of star formation and evolution throughout the universe.
New understanding of solar radiation opacity
In a recent international study led by Gaël Buldgen of the University of Liège, scientists applied helioseismic techniques to independently measure how the sun's deep plasma absorbs high-energy radiation. This groundbreaking research provides new insights into solar radiation opacity, a key factor in understanding how matter and radiation interact in the extreme conditions of the solar core.
The findings are consistent with observations from renowned institutions such as Sandia National Laboratories and ongoing research at Livermore National Laboratory, while also highlighting gaps in our understanding of atomic physics. Notably, the study revealed differences in theoretical predictions by teams from Los Alamos National Laboratory, Ohio State University, and the CEA Research Center Saclay in Paris, France, underscoring the need for further research.
Unprecedented stellar modeling accuracy
The research team leveraged ULiège's expertise in helioseismology and stellar modeling and used advanced numerical tools developed at the school. Gaël Buldgen explains: "By detecting solar sound waves with unparalleled precision, we can reconstruct the internal properties of stars, just as we infer the properties of a musical instrument from the sound it emits."
The precision of helioseismic measurements is extraordinary: They allow us to estimate the mass of a cubic centimeter of material inside the Sun with an accuracy that exceeds that of a high-precision kitchen scale, without ever seeing or touching the material. Solar activity science was developed at the end of the twentieth century and played an important role in advancing fundamental physics. In particular, it has contributed to major discoveries such as neutrino oscillations, which were recognized by the 2015 Nobel Prize. These developments suggest that the origin of this phenomenon cannot be attributed to solar models. However, with the 2009 revision of the sun's chemical composition (confirmed in 2021), adjustments will still need to be made. This revision created a crisis for solar models, which were no longer consistent with helioseismic observations.
To address this challenge, the University of Liège developed advanced tools, initially as part of PhD work and later enriched through international collaborations in Birmingham and Geneva. These tools make it possible to reexamine the internal thermodynamic conditions of the Sun and revisit questions that were once ignored by the scientific community. Meanwhile, work in 2015 by James Bailey of Sandia National Laboratories highlighted the critical role of radiation opacity. Initial experimental measurements showed significant differences from theoretical predictions and were met with some skepticism.
Guide future experiments and research
Today's helioseismic measurements provide valuable confirmation and make it possible to specify in which temperature, density and energy regions these experiments should focus in order to better reproduce solar conditions. Furthermore, while Z machine experiments are extremely valuable, their energy and financial costs are prohibitive. On the other hand, heliseismic measurements offer an economical supplementary option while also guiding the experimenter to the optimal window for laboratory measurements.
The research has implications far beyond stellar modeling. It improves the accuracy of theoretical models used to estimate the ages and masses of stars and exoplanets, thereby contributing to our understanding of galactic evolution and stellar populations.
"The Sun is an important calibrator of our star's evolution and the laboratory of choice for discovering whether we are on the right track. These results are even more important as we prepare to launch the PLATO satellite in 2026, one of whose goals is to accurately characterize solar-type stars in order to find habitable terrestrial planets "What's more, these results have resonance in the context of nuclear fusion, as the Sun remains the only stable fusion reactor in the solar system. "Improving our understanding of the conditions inside the Sun has direct implications for fusion energy research, which is a key issue in developing clean energy solutions," added Gaël Buldgen.
These results highlight the need to improve existing atomic models to account for the discrepancy between experimental observations and theoretical calculations. These advances will redefine our understanding of stellar evolution and the physical processes that govern stellar structure and evolution. This research confirms the University of Liège's position at the forefront of astrophysics science and demonstrates the key role of helioenergetics in unraveling the mysteries of the universe.
Compiled from /ScitechDaily