The Role of the Magnetorotational Instability in Massive Stars

Understand

The magnetorotational instability (MRI) is key physics in accretion disks and is widely considered to play some role in massive-star core collapse.

• Models of rotating massive stars naturally develop very strong shear at composition boundaries, a necessary condition for MRI instability, and the MRI is subject to triply-diffusive destabilizing effects in radiative regions.
• We have used the MESA stellar evolution code to compute magnetic effects due to the Spruit-Taylor mechanism and the MRI, separately and together, in a sample of massive star models.
• We find that the MRI can be active in the later stages of massive star evolution, leading to mixing effects that are not captured in models that neglect the MRI.