3D Simulations of Oxygen Shell Burning with and without Magnetic Fields

Understand

We present a first 3D magnetohydrodynamic (MHD) simulation of convective oxygen and neon shell burning in a non-rotating $18\, M_\odot$ star shortly before core collapse to study the generation of magnetic fields in supernova progenitors.

• We also run a purely hydrodynamic control simulation to gauge the impact of the magnetic fields on the convective flow and on convective boundary mixing.
• After about 17 convective turnover times, the magnetic field is approaching saturation levels in the oxygen shell with an average field strength of $\mathord{\sim}10^{10}\, \mathrm{G}$, and does not reach kinetic equipartition.
• The field remains dominated by small to medium scales, and the dipole field strength at the base of the oxygen shell is only $10^{9}\, \mathrm{G}$.