2016MNRAS.460.1811S

We present our analysis of HD 35502 based on high- and medium-resolution spectropolarimetric observations. Our results indicate that the magnetic B5IVsnp star is the primary component of a spectroscopic triple system and that it has an effective temperature of 18.4±0.6 kK, a mass of 5.7±0.6 M_☉, and a polar radius of 3.0^{+1.1}_{-0.5} R_☉. The two secondary components are found to be essentially identical A-type stars for which we derive effective temperatures (8.9±0.3 kK), masses (2.1±0.2 M_☉), and radii (2.1±0.4 R_☉). We infer a hierarchical orbital configuration for the system in which the secondary components form a tight binary with an orbital period of 5.668 66(6) d that orbits the primary component with a period of over 40 yr. Least-Squares Deconvolution profiles reveal Zeeman signatures in Stokes V indicative of a longitudinal magnetic field produced by the B star ranging from approximately -4 to 0 kG with a median uncertainty of 0.4 kG. These measurements, along with the line variability produced by strong emission in Hα, are used to derive a rotational period of 0.853 807(3) d. We find that the measured v sin i=75±5 km s^-1 of the B star then implies an inclination angle of the star's rotation axis to the line of sight of 24⁺⁶_–10 ^○. Assuming the Oblique Rotator Model, we derive the magnetic field strength of the B star's dipolar component (14^{+9}_{-3} kG) and its obliquity (63±13°). Furthermore, we demonstrate that the calculated Alfven radius (41^{+17}_{–6}R*) and Kepler radius (2.1^{+0.4}_{–0.7}R*) place HD 35502's central B star well within the regime of centrifugal magnetosphere-hosting stars.