Strongly Bipolar Inner Ejecta of the Normal Type IIP Supernova ASASSN-16at
Strongly Bipolar Inner Ejecta of the Normal Type IIP Supernova ASASSN-16at
We report distinctly double-peakedH-alpha and H-beta emission lines in the late-time, nebular-phase spectra (>~200 d) of the otherwise normal at early phases (<~ 100 d) Type IIP supernova ASASSN-16at (SN 2016X). Such distinctly double-peaked nebular Balmer lines have never been observed for a Type II SN. The nebular-phase Balmer emission …