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The rotational and magnetic properties of many magnetic hot stars are poorly characterized, therefore the Magnetism in Massive Stars and Binarity and Magnetic Interactions in various classes of Stars collaborations have collected extensive high-dispersion spectropolarimetric data sets of these targets. We present longitudinal magnetic field measurements (Bz) for 52 early B-type stars (B5-B0), with which we attempt to determine their rotational periods Prot. Supplemented with high-resolution spectroscopy, low-resolution Dominion Astrophysical Observatory circular spectropolarimetry, and archival Hipparcos photometry, we determined Prot for 10 stars, leaving only five stars for which Prot could not be determined. Rotational ephemerides for 14 stars were refined via comparison of new to historical magnetic measurements. The distribution of Prot is very similar to that observed for the cooler Ap/Bp stars. We also measured v sin i and vmac for all stars. Comparison to non-magnetic stars shows that v sin i is much lower for magnetic stars, an expected consequence of magnetic braking. We also find evidence that vmac is lower for magnetic stars. Least-squares deconvolution profiles extracted using single-element masks revealed widespread, systematic discrepancies in (Bz) between different elements: this effect is apparent only for chemically peculiar stars, suggesting it is a consequence of chemical spots. Sinusoidal fits to H line (Bz) measurements (which should be minimally affected by chemical spots), yielded evidence of surface magnetic fields more complex than simple dipoles in six stars for which this has not previously been reported; however, in all six cases, the second- and third-order amplitudes are small relative to the first-order (dipolar) amplitudes. [ABSTRACT FROM AUTHOR]

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 ± 0.6M☉, and a polar radius of 3.0--0.5+1.1 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 ± 0.2M☉), and radii (2.1 ± 0.4R☉). 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 kms-1 of the B star then implies an inclination angle of the star's rotation axis to the line of sight of 24-10+6°. Assuming the Oblique Rotator Model, we derive the magnetic field strength of the B star's dipolar component (14-3+9 kG) and its obliquity (63 ± 13 deg). Furthermore, we demonstrate that the calculated Alfvén radius (41-6+17 R*) and Kepler radius (2.1-0.7+0.4 R*) place HD 35502's central B star well within the regime of centrifugal magnetosphere-hosting stars. [ABSTRACT FROM AUTHOR]

A new time series of high-resolution Stokes I and V spectra of the magnetic B2V star HD 184927 has been obtained in the context of the Magnetism in Massive Stars Large Program with an Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) spectropolarimeter at the Canada-France-Hawaii Telescope and dimaPol liquid crystal spectropolarimeter at 1.8-m telescope of Dominion Astrophysical Observatory. We model the optical and UV spectrum obtained from the International Ultraviolet Explorer (IUE) archive to infer the stellar physical parameters. Using magnetic field measurements, we derive an improved rotational period of 9.531 02 ± 0.0007 d. We infer the longitudinal magnetic field from lines of H, He, and various metals, revealing large differences between the apparent field strength variations determined from different elements. Magnetic Doppler Imaging using He and O lines yields strongly non-uniform surface distributions of these elements. We demonstrate that the diversity of longitudinal field variations can be understood as due to the combination of element-specific surface abundance distributions in combination with a surface magnetic field that is comprised of dipolar and quadrupolar components. We have reanalysed IUE high-resolution spectra, confirming strong modulation of wind-sensitive C IV and S IV resonance lines. However, we are unable to detect any modulation of the H profile attributable to a stellar magnetosphere. We conclude that HD 184927 hosts a centrifugal magnetosphere (η*; 2.4+22-1.1 x 104), albeit one that is undetectable at optical wavelengths. The magnetic braking time-scale of HD 184927 is computed to be τJ = 0.96 or 5.8 Myr. These values are consistent with the slow rotation and estimated age of the star. [ABSTRACT FROM AUTHOR]