{"paper":{"title":"Strongly Bipolar Inner Ejecta of the Normal Type IIP Supernova ASASSN-16at","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.SR"],"primary_cat":"astro-ph.HE","authors_text":"Antonia Morales-Garoffolo, A. Siviero, Auni Somero, B. J. Shappee, C. Ashall, Christa Gall, C. S. Kochanek, David Bersier, D. Grupe, F. Onori, Giacomo Terreran, H. Kuncarayakti, J. L. Prieto, K. Z. Stanek, L. Tomasella, M. D. Stritzinger, M. Gromadzki, N. Elias-Rosa, Nidia Morrell, Ping Chen, Seppo Mattila, Stefano Benetti, Subhash Bose, Subo Dong (KIAA-PKU), Thomas M Reynolds, Todd A. Thompson, T. W.-S. Holoien","submitted_at":"2018-10-29T18:00:01Z","abstract_excerpt":"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 is driven by the radioactive Co56 decay, so the observed line-profile bifurcation suggests a strong bipolarity in the Ni56 distribution or in the line-forming region of the inner ejecta. The strongly bifurcated blue- and red-shifted peaks are separated by ~3x1"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1810.12304","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}