In the minutes before a massive star becomes a supernova, a hidden drama unfolds in its depths. A giant cauldron boils: matter churns, rotates, and invisible magnetic threads snap and rejoin. This moment, which has eluded direct observation, has now been recreated for the first time in three-dimensional computer models.
The authors of the study tracked the lives of two compact Wolf–Rayet stars: these are the stripped, nearly envelope-free cores of former giants. The calculations showed that closer to the center, rotation no longer resembles a layered onion, where each layer spins at its own speed. Instead, it aligns into cylinders — material at the same distance from the axis rotates almost uniformly, regardless of depth. This profile, close to the law where velocity falls off inversely with the square of the distance from the axis, arises from powerful flows that stir the interior like giant paddles.
The big surprise is magnetic connectivity. In old one-dimensional models, each layer of the star lived in isolation, and magnetic loops never crossed its boundaries. The three-dimensional simulation shatters these partitions: fields pierce adjacent regions, creating a single network. Isolated rooms in a house suddenly connect via open corridors, and a draft sweeps through the entire building.
Such restructuring is critical for the final chord. When the core collapses into a neutron star or black hole, the rotation and magnetic fields inherited from the progenitor will determine how powerful the explosion is and whether a gravitational wave is born. The new data allow collapse simulations to start from physically justified initial conditions rather than invented ones, as if we finally have a clear snapshot of the spring before it uncoils.
The rotation speed at the center of such a star can reach tens of revolutions per second — faster than helicopter blades.
In Stanisław Lem's novel 'Solaris', the planet's ocean exhibits unpredictable magnetic activity — somewhat akin to the chaos in the depths of a dying star.