CFHT UM2019 - Presentation Details

Abstract Details

Title: Modeling the Topology of NGC1624-2’s Giant Magnetic Field

Presenter: Rebecca Macinnis


NGC 1624-2 possesses the strongest magnetic field of any O-star (~20 kG). We present evidence from ESPaDONs spectropolarimetric data that this star may also be the first O-star with a significant non-dipolar component to its magnetic field. We acquired 9 observations covering the full rotational period of NGC 1624-2. The maximal longitudinal field is 5.27±0.7 kG, which is in agreement with the initial measurements of 5.35±0.5 kG from the two discovery observations presented in Wade et al. (2012). Because of the strong magnetic field, Zeeman splitting is seen in the Stokes-I profiles, making the addition of new constraints to the magnetic field model possible. We used a simple polarized line profile model to simultaneously reproduce the Stokes-I and Stokes-V profiles. We are unable to accurately replicate the patterns observed from ESPaDOnS with any dipolar topology, leading us to conclude that NGC 1624-2 is the first O-star with a magnetic field more complicated than a simple dipole. These new constraints will be used to model the star's magnetospheric emission at optical (CFHT), X-ray (Chandra), and UV (HST) wavelengths.