Polarization Variability Hints at Dust Morphology Changes Around Wolf-Rayet Binary CV Serpentis

Some types of massive Wolf-Rayet binaries produce significant amounts of carbonaceous material, which enriches the Galaxy with dust. Recent studies have proved that the dust created in these ``WCd" binaries survives for hundreds of years. However, all previous studies have focused on WR binary systems with long orbital periods, leaving a gap in our understanding of the dust contribution from short-period WCd binaries. CV Serpentis represents such a system, with a circular orbital period of 29.7 days. While it has been shown to produce dust, it is still unknown whether CV Ser forms its dust within the circular binary orbit or whether it reveals a larger-scale system architecture. We present new spectropolarimetric data on CV Ser repeatedly sampling the orbital phase from 2017-2022. The polarization is caused by light scattering in ionized gas and/or dust in the system, so by measuring this polarization in both the emission lines and the continuum, we can reveal changes in the stellar winds and the geometry of the circumstellar material as a function of orbital period. Additionally, we compare our spectropolarimetric data with photopolarimetric data from 1987-1988. Over the last 30 years, we find changes in both the magnitude and the orientation of the polarization. It is possible that the changes we observed since 1987 imply a long-term variation in its circumstellar structure, which could be due to movement of massive dust clumps or a long-period wind interaction with a previously undiscovered stellar companion.