The magnetic, spectroscopic, and photometric variability of the Wolf-Rayet star WR 55

Abstract

Studies of magnetic fields in the most evolved massive stars, the Wolf-Rayet stars, are of special importance because they are progenitors of certain types of supernovae. The first detection of a magnetic field of the order of a few hundred gauss in the WN7 star WR 55, based on a few FORS2 low-resolution spectropolarimetric observations, was reported in 2020. In this work, we present new FORS2 observations allowing us to detect magnetic and spectroscopic variability with a period of 11.90 h. No significant frequencies were detected in TESS and ASAS-SN photometric observations. Importantly, magnetic field detections are achieved currently only in two Wolf-Rayet stars, WR 6 and WR 55, both showing the presence of corotating interacting regions.