Small-scale magnetic fields of binary stars

This work aims to investigate the small-scale magnetic fields of a pair of binary T Tauri stars, V1878 Ori and V4046 Sgr. This is done in order to provide a more complete picture of their magnetic field, as so far only the large-scale structures have been studied using Zeeman Doppler imaging (ZDI) by Lavail et al. (2020) and Donati et al. (2011) respectively. In addition, the two binaries have very similar components, indicating that the magnetic field generation should be similar for the two components. We use observations taken by ESPaDOnS at the CFHT. In order to study the small scale fields we use Zeeman intensification, an effect that increases the equivalent widths of spectral lines in the presence of magnetic fields. We find that the magnetic fields on the components are similar to each other. This is in contrast to the large-scale fields which show significant difference in both strength and structure. Our results indicate that the small-scale fields is a more stable measure of the magnetic dynamo whereas the large-scale fields of cool stars are prone to variability.