Active Physics & Astronomy Climate, Earth & Environment

Magnetism in Intermediate and Massive Stars

In plain English

AI plain-English summary

Stars spin down far faster than standard stellar models predict, and the missing mechanism may be magnetism deep inside their cores. Asteroseismology—the study of stellar oscillations—has revealed that stars transport angular momentum far more efficiently than one-dimensional models account for, and that convective cores may be up to 50% larger than predicted. These discrepancies point to missing physics: the interplay of convection, waves, rotation, and magnetic fields. This project will run multi-dimensional magnetohydrodynamical simulations of massive star interiors to answer three questions: how magnetic fields affect mixing at the core boundary, how they transport angular momentum, and how they interact with the gravity-mode pulsations that asteroseismology detects. This is fundamental science. There is no immediate practical application. But getting the physics right inside stars directly shapes predictions for supernova explosions and the properties of the neutron stars and black holes they leave behind. Those predictions underpin gravitational-wave astronomy, nucleosynthesis yields, and our understanding of how galaxies evolve. Better models now mean more reliable interpretations of the data that TESS, PLATO, and future missions will return.

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Asteroseismology - the study of oscillations in stars- has brought about a revolution in stellar astrophysics. Alongside providing precise masses, ages and radii of field stars, asteroseismology has found fundamental discrepancies between observations and one-dimensional (1D) stellar evolution models. The most fundamental of these discrepancies are associated with interior rotation and chemical mixing. For example, asteroseismology has shown that stars across the HR diagram have very efficient angular momentum transport between convective and radiative regions, and that convective core masses of stars are underestimated by as much as 50%, likely due to enhanced mixing at this interface. These observational constraints will only become more stringent as asteroseismology matures and missions such as TESS and PLATO continue to return important data. If we are to optimise learning from these exquisite observations, theoretical models must move beyond 1D to understand the dynamical, multi-dimensional processes that shape stars: convection, waves, magnetism and rotation. The goal of this project is to conduct multi-dimensional magnetohydrodynamical (MHD) simulations of massive star interiors to better understand these processes and, if possible, build better 1D prescriptions. In particular, the proposed simulations will focus on magnetism, building on the PL’s extensive work on convection and waves in multi-dimensional hydrodynamic simulations. Using advanced MHD simulations, the PL and her team will answer some foremost questions brought by modern asteroseismology: (Q1) how does the presence of a magnetic field affect CBM, (Q2) how does a magnetic field impact angular momentum transport, and (Q3) how does the magnetic field interact with waves and impact the gravity-mode pulsations observed by asteroseismology. Answering these questions not only impacts stellar astrophysics and stellar evolution but has a direct impact on understanding supernova yields and the compact objects remaining after their explosions.

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Researchers

Tamara Rogers (Principal Investigator)

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Original classification

Research and Innovation

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