Title: The MiMeS Survey of Magnetism in Stars: B Stars
Presenter: Tali Natan
Abstract:
The Magnetism in Massive Stars (MiMeS) survey collected over 4800 circularly polarized spectra of 560 massive stars using three instruments including ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada-France-Hawaii Telescope. Analysis of the survey’s 108 O-type stars found a magnetic incidence of 7±3%. A further study of the observational biases for O-type stars with no magnetic field detection found that the Initial Magnetic (B) field Function (IBF) is likely bimodal; young O-type stars either have a weak/absent or a strong magnetic field. We present a similar analysis for the MiMeS sample of 215 B-type stars. If the observational biases are comparable between O and B stars, we can better compare magnetic incidence/strength between spectral types. Furthermore, this work serves as a comparison sample to the MiMeS classical Be star sample, for which no magnetic field are detected. The origin of fossil fields and their mechanisms for survival is currently unknown, but progress towards answering these questions is facilitated by accurate population measurements and an understanding of the detection upper limits and selection biases.