2020ApJ...900..162G

We report on over 13 yr of optical and near-ultraviolet spectropolarimetric observations of the famous luminous blue variable (LBV) P Cygni. In the lives of the most massive stars, LBVs are a critical transitional phase and achieve the largest mass-loss rates of any group of stars. Using spectropolarimetry, we are able to learn about the geometry of the near-circumstellar environment surrounding P Cygni and gain insights into LBV mass loss. Using data from the HPOL and WUPPE spectropolarimeters, we estimate the interstellar polarization contribution to P Cygni's spectropolarimetric signal, analyze the variability of the polarization across the Hα emission line, search for periodic signals in the data, and introduce a statistical method to search for preferred position angles in deviations from spherical symmetry that is novel to astronomy. Our data are consistent with previous findings, showing free electron scattering off of clumps uniformly distributed around the star. This is complicated, however, by structure in the percent polarization of the Hα line and a series of previously undetected periodicities.