Magnetic Upper Limits of the MiMeS Be Star Sample

Within the past few decades, spectropolarimetric surveys have discovered that 10% of massive O-, B-, and A-type stars are host to strong, globally organized magnetic fields. Based on the current understanding of magnetism in stars, these fields are not expected and as such their origins are not well understood. However, this 10% magnetic incidence is not observed for a certain subset of massive stars known as Be stars. Be stars are B-type stars with near critical rotation speeds and Balmer emission lines that originate from a Keplerian disk. For these reasons, measuring magnetic fields in Be stars is incredibly difficult and so far none have been found to possess unambiguously-detected fields. Those difficulties could also mean that Be stars might possess magnetic fields but their signatures are completely masked by noise. To further explore Be stars and their observational biases, it is important to have solid constraints on the upper limits on the magnetic field strength as they help us determine if the non-magnetic Be star model is truly consistent with the lack of detected fields. Using a novel method that combines observations and synthetic models, we are able to increase the signal-to-noise ratio of spectropolarimetric observations. Then using a Bayesian statistical method we obtained more accurate estimates of the magnetic field strength upper limits on our sample of Be stars.