Establish the threshold for dynamically significant weak wind confinement

Establish the threshold value of the wind magnetic confinement parameter η* below which a magnetic field is dynamically insignificant in the wind of a massive star.

Background

The authors estimate that ξ Per could have weak magnetic confinement with η* around 0.1–0.16. They note that this weak-confinement regime has been scarcely explored with magnetohydrodynamic simulations, leaving no agreed threshold for when magnetic effects cease to produce dynamically meaningful deviations from spherical wind outflow.

References

Further, it should also be noted that the weak confinement limit has been scarcely explored with MHD simulations, such that there is no consensus threshold value of η* below which a magnetic field would be considered as dynamically insignificant for a massive star's wind.

— Rotation period of the O giant xi Persei: Coexistence of cyclic and periodic variability. A weakly magnetic candidate star  (2610.12323 - Henrichs et al., 8 Oct 2026) in Section 8.3, “Wind magnetic confinement”