Photopolarimetry of semi-regular variable V CVn

Instead, we observe a small lead or lag in relation to the brightness minimum, spanning a period of a few days up to three weeks. Furthermore, the PA sometimes exhibits a non-negligible rotation, especially at lower polarization levels. To elucidate the unusual optical behavior of V CVn, we present a list of literature sources that also exhibit polarization variability with a roughly fixed PA.

We find this correlation occurs in stars with high tangential space velocities, for instance, 'runaway' stars, suggesting that the long-term constant PA is related to how the circumstellar gas is shaped by the star's high-speed motion through the interstellar medium.