Final Report Summary - CHASM (Convective Heat Transport and Stellar Magnetism)
Convection and magnetism are ubiquitous in stars and planets. All stars transport some of their energy by convective motions; so do many substellar objects (like planets or brown dwarfs). Magnetism is likewise common to many of these objects: the most famous example is our Sun, whose 22-year cycle of magnetic activity affects our society in myriad ways. Broadly, the CHASM project sought to develop more realistic models of the convection and magnetism in stellar and planetary interiors. Our work aimed, for example, to understand how the flows and fields depend on bulk stellar/planetary properties, and what effects these processes have on the overall structure and evolution of these objects. We used a multi-pronged approach involving both global-scale 3-D magnetohydrodynamic calculations — which model phenomena in great detail but can only capture a limited period in a star’s life — together with more localised simulations and analytical (or semi-analytical) theory. Our work yielded significant insight into how the convection, and in turn the magnetism, depends on the rotation rate or mass of the star. We also provided new constraints on how dynamo-generated fields rise to the surface of a star where they can be observed, how rotation and magnetism affect stellar radii, and how strong the magnetism can ultimately become.