Large-scale magnetic fields at the surface of massive stars do not only influence the outer-most layers of the star , but also have consequences for the deep interior , only observationally accessible through asteroseismology .
We performed a detailed characterization of the dipolar magnetic field at the surface of the B3.5V star HD 43317 , a SPB/ \beta Cep hybrid pulsator , by studying the rotationally modulated magnetic field of archival and new Narval spectropolarimetry .
Additionally , we employed a grid-based approach to compare the Zeeman signatures with model profiles .
By studying the rotational modulation of the He lines in both the Narval and HARPS spectroscopy caused by co-rotating surface abundance inhomogeneities , we updated the rotation period to 0.897673 \pm 0.000004 d. The inclination angle between the rotation axis and the observer ’ s line of sight remains ill-defined , because of the low level of variability in Stokes V and deformations in the intensity profiles by stellar pulsation modes .
The obliquity angle between the rotation and magnetic axes is constrained to \beta \in [ 67 , 90 ] ^ { \circ } , and the strength of the dipolar magnetic field is of the order of 1 kG to 1.5 kG .
This magnetic field at the stellar surface is sufficiently strong to warrant a uniformly rotating radiative envelope , causing less convective core overshooting , which should be visible in future forward seismic modeling .