Data from: Powering ganymede’s dynamo with protracted core formation

Ganymede is the only known moon with an active dynamo today. Previous
studies interpret Ganymede’s dynamo as arising from convection in a metal
core that formed billions of years ago. However, Ganymede likely accreted
too cold to form with a metal core, which confounds interpretations of
Ganymede’s magnetic field as a constraint on the moon’s broader history.
Here we re-evaluate the thermal evolution of Ganymede’s rock-metal
interior from a cold start. Our models show that Ganymede’s observed
dynamo is consistent with ongoing core formation—a process not yet
observed elsewhere. If Ganymede has an Fe-FeS core with a sub-eutectic
composition, then gradual mantle warming may expel dense Fe melt onto the
growing protocore and stir liquid metal, sustaining a dynamo for billions
of years.