Spectropolarimetry of the type IIP supernova 2021yja: an unusually high continuum polarization during the photospheric phase

Understand

We present six epochs of optical spectropolarimetry of the Type IIP supernova (SN) 2021yja ranging from $\sim$ 25 to 95 days after the explosion.

• An unusually high continuum linear polarization of $p \sim 0.9\%$ is measured during the early photospheric phase, followed by a steady decrease well before the onset of the nebular phase.
• This behavior has not been observed before in Type IIP supernovae (SNe IIP).
• The observed continuum polarization angle does not change significantly during the photospheric phase.