Why polarimetry?
Photometry is extremely sensitive to stellar variability, but it is not always enough to identify the geometry of a pulsation mode. Polarimetry carries complementary information because it responds to departures from circular symmetry on the stellar disk. That makes it a promising observable for non-radial pulsations, especially when combined with photometry and spectroscopy.
Massive-star applications
Massive O- and B-type stars are difficult to probe internally, but their oscillations carry information about mixing, rotation, and later evolutionary outcomes. The β Crucis work demonstrated a modern route: combine polarimetry, space photometry, and spectroscopy to identify pulsation geometry in a bright β Cephei star.
Next directions
Ongoing polarimetric time-series work: observing strategy, mode-identification diagnostics, amplitude and phase comparisons across passbands, and examples connecting optical/NIR/UV measurements to stellar pulsation models.