Oe stars are a subset of the O-type stars that exhibit double-peaked or central emission in spectra of their Balmer lines. This emission-line morphology is distinct from signatures of stellar winds, and instead indicates the presence of a circumstellar disk. It is thought that these stars are a continuation of the Be phenomenon toward hotter spectral types.
The recent detection of magnetic fields in several O-type stars suggests a possible explanation for the stability of disk-like structures around Oe stars. According to this hypothesis, the disk is the wind of the star, which has been channelled by an approximately dipolar magnetic field so that outflowing material from the opposite hemispheres collides near the magnetic equator.
This poster will present spectropolarimetric observations of the hottest Galactic Oe star HD 155806, obtained with ESPaDOnS at CFHT within the context of the MiMeS collaboration, and their implications for such magnetic disc models.