Magneto-Archeology of White Dwarfs: Discovering a magnetic pathway from red-giant cores to cold white dwarfs

Newly accepted A&A Letter to the Editor: Einramhof+ 2026 !

The detection of strong, large-scale magnetic fields at the surface of mainly the oldest population of white dwarfs points towards a hidden internal magnetic field slowly rising to the surface. We revisit the fossil field framework by using the asteroseismic detections to constrain the strength of such magnetic fields as they evolve to the white dwarf stage. We find that a broadly magnetized internal radiative zone during the red giant branch is key for the fossil field theory to connect magnetic fields observed along the late evolution of stars.