J/ApJ/873/L3ivo://CDS.VizieR/J/ApJ/873/L3doi:10.26093/cds/vizier.18739003CDSBose S.Dong S.Elias-Rosa N.Shappee B.J.Bersier D.Benetti S.,Stritzinger M.D.Grupe D.Kochanek C.S.Prieto J.L.Chen P.,Kuncarayakti H.Mattila S.Morales-Garoffolo A.Morrell N.Onori F.,Reynolds T.M.Siviero A.Somero A.Stanek K.Z.Terreran G.,Thompson T.A.Tomasella L.Ashall C.Gall C.Gromadzki M.,Holoien T.W.-S.2020-10-08T09:21:49Z2020-09-08T08:19:18ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsupernovaeultraviolet-photometryinfrared-photometryvisible-astronomybroad-band-photometryWe report distinctly double-peaked H{alpha} and H{beta} emission lines in the late-time, nebular-phase spectra (>~200 days) of the otherwise normal at early phases (<~100 days) type IIP supernova ASASSN-16at (SN2016X). 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 ^56^Co decay, so the observed line profile bifurcation suggests a strong bipolarity in the ^56^Ni distribution or in the line-forming region of the inner ejecta. The strongly bifurcated blueshifted and redshifted peaks are separated by ~3x10^3^km/s 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 ~100 days.2019ApJ...873L...3Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/873/L3CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)B/chandra : The Chandra Archive Log (CXC, 1999-2014)B/eso : ESO Science Archive Catalog (ESO, 1991-2020)VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)J/ApJ/756/173 : Photom. of type IIn SNe 2005ip & 2006jd (Stritzinger+, 2012)J/MNRAS/433/1871 : UBVRI griz light curves of SN 2012aw (Bose+, 2013)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/MNRAS/444/527 : Tully-Fisher distances for Spitzer galaxies (Sorce+, 2014)J/MNRAS/448/2608 : UV and opt. photometric data for SN 2013by (Valenti+, 2015)J/ApJ/799/208 : Type IIP supernovae from Pan-STARRS1 (Sanders+, 2015)J/A+A/580/A142 : SN 2011dh. The first two years (Ergon+, 2015)J/MNRAS/471/4966 : ASAS-SN bright supernova catalogue 2016 (Holoien+, 2017)J/ApJ/861/63 : Type IIP SN 2016bkv LCs and spectra (Hosseinzadeh+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/873/L3https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/873/L3http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/873/L3https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/873/L3https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/873/L3http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/873/L3GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap3.377399441402775e-19 1.2058628298368645e-18UVOpticalInfrareddefaultJ/ApJ/873/L3/table2*Optical and NIR photometry of ASASSN-16atrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSet"Opt" or "NIR"meta.idcharDateUT date of observationtime.epoch;obsnullableJD[7406.99/8533.62] Julian date of observation; JD-2450000dtime.epochfloatPhase[0.57/1127.2] Days since the explosion epoch JD 2457406.42dtime.epochfloatBmag[14.2/18.8]? B-band magnitudemagphot.mag;em.opt.Bfloatnullablee_Bmag[0.017/1.3]? Bmag uncertaintymagstat.error;phot.magfloatnullableVmag[14/19.1]? V-band magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag[0.02/1.8]? Vmag uncertaintymagstat.error;phot.magfloatnullableumag[13.9/20.9]? u-band magnitudemagphot.mag;em.opt.Ufloatnullablee_umag[0.06/0.3]? umag uncertaintymagstat.error;phot.magfloatnullablegmag[14/22.1]? g-band magnitudemagphot.mag;em.opt.Bfloatnullablee_gmag[0.02/0.5]? gmag uncertaintymagstat.error;phot.magfloatnullablermag[14/21.8]? r-band magnitudemagphot.mag;em.opt.Rfloatnullablee_rmag[0.012/0.3]? rmag uncertaintymagstat.error;phot.magfloatnullableimag[14.1/22.7]? i-band magnitudemagphot.mag;em.opt.Ifloatnullablee_imag[0.011/0.7]? imag uncertaintymagstat.error;phot.magfloatnullablezmag[14.3/22.1]? z-band magnitudemagphot.mag;em.opt.Ifloatnullablee_zmag[0.013/0.5]? zmag uncertaintymagstat.error;phot.magfloatnullableKmag[14.8/19]? K-band magnitudemagphot.mag;em.IR.Kfloatnullablee_Kmag[0.05/0.6]? Kmag uncertaintymagstat.error;phot.magfloatnullableTelTelescope and instrument (1)instrcharJ/ApJ/873/L3/table2b*NUV photometry of ASASSN-16atrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSet"NUV"meta.idcharDateUT date of observationtime.epoch;obsnullableJD[7408.58/7452.83] Julian date of observation; JD-2450000dtime.epochfloatPhase[2.16/46.41] Days since the explosion epoch JD 2457406.42dtime.epochfloatUVW2mag[12.7/18.9]? Swift/UVOT UVW2 magnitudemagphot.mag;em.UVfloatnullablee_UVW2mag[0.03/0.3]? UVW2mag uncertaintymagstat.error;phot.magfloatnullableUVM2mag[12.6/19.5]? Swift/UVOT UVM2 magnitudemagphot.mag;em.UVfloatnullablee_UVM2mag[0.03/0.4]? UVM2mag uncertaintymagstat.error;phot.magfloatnullableUVW1mag[12.7/17.8]? Swift/UVOT UVW1 magnitudemagphot.mag;em.UVfloatnullablee_UVW1mag[0.03/0.2]? UVW1mag uncertaintymagstat.error;phot.magfloatnullableUmag[12.9/16.4]? Swift/UVOT U magnitudemagphot.mag;em.opt.Ufloatnullablee_Umag[0.03/0.08]? Umag uncertaintymagstat.error;phot.magfloatnullableBmag[14.2/15.7]? Swift/UVOT B magnitudemagphot.mag;em.opt.Bfloatnullablee_Bmag[0.03/0.05]? Bmag uncertaintymagstat.error;phot.magfloatnullableVmag[14.1/14.9]? Swift/UVOT V magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag[0.03/0.06]? Vmag uncertaintymagstat.error;phot.magfloatnullableTelTelescope and instrument (always "UVOT")instrchar