Supernova Explosions: Lessons from Spectropolarimetry

Supernova can be polarized by an asymmetry in the explosion process, an off-center source of illumination, scattering in an envelope distorted by rotation or a binary companion, or scattering by the circumstellar dust. Careful polarimetry is the most powerful tool to study the 3-D geometry of supernovae. A deep understanding of the 3-D geometry of SNe is essential in using them for calibrated distance indicators.