| Title | Strongly Bipolar Inner Ejecta of the Normal Type IIP Supernova ASASSN-16at |
| Authors | Bose, Subhash Dong, Subo Elias-Rosa, N. Shappee, B. J. Bersier, David Benetti, Stefano Stritzinger, M. D. Grupe, D. Kochanek, C. S. Prieto, J. L. Chen, Ping Kuncarayakti, H. Mattila, Seppo Morales-Garoffolo, Antonia Morrell, Nidia Onori, F. Reynolds, Thomas M. Siviero, A. Somero, Auni Stanek, K. Z. Terreran, Giacomo Thompson, Todd A. Tomasella, L. Ashall, C. Gall, Christa Gromadzki, M. Holoien, T. W-S |
| Affiliation | Peking Univ, Kavli Inst Astron & Astrophys, Yi He Yuan Rd 5, Beijing 100871, Peoples R China CSIC, Inst Space Sci ICE, Campus UAB,Carrer Can Magrans S-N, E-08193 Barcelona, Spain IEEC, C Gran Capita 2-4,Edif Nexus 201, E-08034 Barcelona, Spain Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA Liverpool Sci Pk, Astrophys Res Inst, 146 Brownlow Hill, Liverpool L3 5RF, Merseyside, England Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy Aarhus Univ, Dept Phys & Astron, Ny Munkegade 120, DK-8000 Aarhus C, Denmark Morehead State Univ, Dept Earth & Space Sci, Morehead, KY 40351 USA Ohio State Univ, Dept Astron, 140 West 18th Ave, Columbus, OH 43210 USA Ohio State Univ, CCAPP, 191 West Woodruff Ave, Columbus, OH 43210 USA Univ Diego Portales, Nucleo Astron, Fac Ingn & Ciencias, Av Ej Ercito 441, Santiago, Chile Millennium Inst Astrophys, Santiago, Chile Univ Turku, Finnish Ctr Astron ESO FINCA, FI-20014 Turku, Finland Univ Turku, Tuorla Observ, Dept Phys & Astron, FI-20014 Turku, Finland Univ Cadiz, Dept Appl Phys, Campus Puerto Real, E-11510 Cadiz, Spain Las Campanas Observ, Carnegie Observ, Casilla 601, La Serena, Chile Ist Astrofis & Planetol Spaziali, Via Fosso Cavaliere 100, I-00133 Rome, Italy Univ Padua, Dipartimento Fis & Astron, Via Marzolo 8, I-35131 Padua, Italy Northwestern Univ, CIERA, Evanston, IL 60208 USA Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208 USA Inst Adv Study, 1 Einstein Dr, Princeton, NJ 08540 USA Florida State Univ, Dept Phys, Tallahassee, FL 32306 USA Univ Copenhagen, Dark Cosmol Ctr, Niels Bohr Inst, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark Warsaw Univ, Astron Observ, Ujazdowskie 4, PL-00478 Warsaw, Poland Carnegie Observ, 813 Santa Barbara St, Pasadena, CA 91101 USA |
| Keywords | galaxies: individual (UGC 08041) supernovae: general supernovae: individual (ASASSN-16at, SN 2016X) |
| Issue Date | 2019 |
| Publisher | ASTROPHYSICAL JOURNAL LETTERS |
| Abstract | We report distinctly double-peaked H alpha and H beta emission lines in the late-time, nebular-phase spectra (greater than or similar to 200 days) of the otherwise normal at early phases (less than or similar to 100 days) 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 Co-56 decay, so the observed line profile bifurcation suggests a strong bipolarity in the Ni-56 distribution or in the line-forming region of the inner ejecta. The strongly bifurcated blueshifted and redshifted peaks are separated by similar to 3 x 10(3) km s(-1) and are roughly symmetrically positioned with respect to the host-galaxy rest frame, implying that the inner ejecta are composed of two almost-detached blobs. The red peak progressively weakens relative to the blue peak, and disappears in the 740 days spectrum. One possible reason for the line-ratio evolution is increasing differential extinction from continuous formation of dust within the envelope, which is also supported by the near-infrared flux excess that develops after similar to 100 days. |
| URI | http://hdl.handle.net/20.500.11897/550353 |
| ISSN | 2041-8205 |
| DOI | 10.3847/2041-8213/ab0558 |
| Indexed | SCI(E) |
| Appears in Collections: | 科维理天文与天体物理研究所 |
