Determine whether non-equatorial CIRs produce distinct DAC behaviour

Determine whether DAC behaviour generated by non-equatorial corotating interaction regions differs from the behaviour inferred from simulations of equatorial corotating interaction regions, using models that couple three-dimensional hydrodynamics with radiative-transfer calculations.

Background

The paper proposes that surface spots at moderate-to-high magnetic latitudes could drive corotating interaction regions (CIRs) while remaining largely unaffected by ξ Per’s putative weak magnetic confinement. Existing three-dimensional simulations have examined non-equatorial CIR formation and produced large-scale spiral structures, but those simulations did not include radiative-transfer calculations. Consequently, the observable DAC signatures associated with such structures remain unresolved.

References

Unfortunately, these non-equatorial CIR simulations were not coupled with radiative transfer calculations, so it is not yet known whether the DAC behaviour would differ from what was inferred from simulations of equatorial CIRs.

— 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 8.4, “On the origin of ultraviolet line profile variability in ξ Per”