MAGNIFY · The Quest for MAGNetIc Fields in A and F TYpe Stars

Magnetic fields are ubiquitous and have a substantial impact on galactic, stellar and planetary evolution and on life. Theoretical models imply that magnetic fields can affect stars from the deep interior to the outermost layers at each stage of evolution. Yet the origin, geometry and evolution of magnetic fields often remain a mystery. Consequently, standard stellar evolution models do not consider the interaction of magnetic fields with other physical processes.Extensive surveys show that only 10% of the intermediate-mass A&F-type main-sequence stars have detectable magnetic fields. However, studies show that up to 60% of red giant stars that evolve from these stars have strong internal magnetic fields. Stellar evolution dictates that if the magnetic fields exist in these red giants, they must also exist in younger stars. This discrepancy raises many open questions: Have surface magnetic fields in A&F stars been below the detection threshold of modern instruments? Are their magnetic fields confined to stellar interiors and never penetrate the surface? If so, how may we detect them? Are there physical processes that prevent A and F stars from producing and maintaining stable magnetic fields?MAGNIFY aims at answering these questions by 1) investigating the existence of internal and surface magnetic fields in A&F stars using asteroseismology and 2) exploring the mechanisms producing magnetic fields by studying stellar spots. With asteroseismology, we can use stellar pulsations to probe deep into the stellar interior to detect the presence of hidden magnetic fields. We will use data from the Kepler, TESS and Gaia space missions to study A&F type pulsators and use stellar evolution and pulsation models to disentangle the signatures of magnetic fields from other physical processes. Finally, we will use measurements of stellar spots in a large number of A&F stars to broaden our understanding of magnetic field generation and how it varies with stellar mass and age.