Spectropolarimetry of the Type IIP supernova 2021yja: an unusually high continuum polarization during the photospheric phase Academic Article uri icon

abstract

  • ABSTRACT We present six epochs of optical spectropolarimetry of the Type IIP supernova (SN) 2021yja ranging from 25 to 95d after the explosion. An unusually high continuum linear polarization of $p approx 0.9~{{
    m per cent}}$ is measured during the early photospheric phase, followed by a steady decrease well before the onset of the nebular phase. This behaviour has not been observed before in Type IIP supernovae (SNe IIP). The observed continuum polarization angle does not change significantly during the photospheric phase. We find a pronounced axis of symmetry in the global ejecta that is shared in common with the H and Caii near-infrared triplet lines. These observations are consistent with an ellipsoidal geometry. The temporal evolution of the continuum polarization is also compatible with the SN ejecta interacting with aspherical circumstellar matter (CSM), although no spectroscopic features that may be associated with strong interaction can be identified. Alternatively, we consider the source of the high polarization to be an extended hydrogen envelope that is indistinguishable from low-density CSM.

published proceedings

  • Monthly Notices of the Royal Astronomical Society

author list (cited authors)

  • Vasylyev, S. S., Yang, Y. i., Patra, K. C., Filippenko, A. V., Baade, D., Brink, T. G., ... Zheng, W.

complete list of authors

  • Vasylyev, Sergiy S||Yang, Yi||Patra, Kishore C||Filippenko, Alexei V||Baade, Dietrich||Brink, Thomas G||Hoeflich, Peter||Maund, Justyn R||Patat, Ferdinando||Wang, Lifan||Wheeler, J Craig||Zheng, WeiKang

publication date

  • November 2023