J/ApJ/946/7ivo://CDS.VizieR/J/ApJ/946/7doi:10.26093/cds/vizier/ba-xj-7CDSNi Y.QiMoon D.-S.Drout M.R.Polin A.Sand D.J.Gonzalez-Gaitan S.,Kim S.C.Lee Y.Park H.S.Howell D.A.Nugent P.E.Piro A.L.,Brown P.J.Galbany L.Burke J.Hiramatsu D.Hosseinzadeh G.,Valenti S.Afsariardchi N.Andrews J.E.Antoniadis J.Beaton R.L.,Bostroem K.A.Carlberg R.G.Cenko S.B.Cha S.-M.Dong Y.Gal-Yam A.,Haislip J.Holoien T.W.-S.Johnson S.D.Kouprianov V.Lee Y.,Matzner C.D.Morrell N.McCully C.Pignata G.Reichart D.E.Rich J.,Ryder S.D.Smith N.Wyatt S.Yang S.2026-07-02T11:58:58Z2025-04-07T12:03:48ZCDS support team

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

cds-question@unistra.frinfrared-photometryvisible-astronomybroad-band-photometrysupernovaespectroscopySN 2018aoz is a Type Ia SN with a B-band plateau and excess emission in infant-phase light curves <~1d after the first light, evidencing an over-density of surface iron-peak elements as shown in our previous study. Here, we advance the constraints on the nature and origin of SN2018aoz based on its evolution until the nebular phase. Near-peak spectroscopic features show that the SN is intermediate between two subtypes of normal Type Ia: core normal and broad line. The excess emission may be attributable to the radioactive decay of surface iron-peak elements as well as the interaction of ejecta with either the binary companion or a small torus of circumstellar material. Nebular-phase limits on H{alpha} and HeI favor a white dwarf companion, consistent with the small companion size constrained by the low early SN luminosity, while the absence of [OI] and HeI disfavors a violent merger of the progenitor. Of the two main explosion mechanisms proposed to explain the distribution of surface iron-peak elements in SN 2018aoz, the asymmetric Chandrasekhar-mass explosion is less consistent with the progenitor constraints and the observed blueshifts of nebular-phase [FeII] and [NiII]. The helium-shell double-detonation explosion is compatible with the observed lack of C spectral features, but current 1D models are incompatible with the infant-phase excess emission, B_max_--V_max_ color, and weak strength of nebular-phase [CaII]. Although the explosion processes of SN 2018aoz still need to be more precisely understood, the same processes could produce a significant fraction of Type Ia SNe that appear to be normal after ~1d.2023ApJ...946....7Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/946/7CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-)J/AJ/135/1598 : Optical spectroscopy of type Ia supernovae (Matheson+, 2008)J/ApJ/699/L139 : Spectral parameters of SNe Ia (Wang+, 2009)J/AJ/143/126 : Spectroscopy of nearby Type Ia supernovae (Blondin+, 2012)J/ApJ/753/22 : Swift/UVOT observations of SN 2011fe (Brown+, 2012)J/other/NewA/20.30 : BVRI light curves of 3 SN (Munari+, 2013)J/A+A/554/A27 : 2011fe spectrophotometric time series (Pereira+, 2013)J/other/Sci/340.170 : Classifications of 188 SNe Ia (Wang+, 2013)J/ApJ/787/29 : UVOT phot. of Super-Chandrasekhar mass SNe Ia (Brown+, 2014)J/MNRAS/444/3258 : Velocities and EW of PTF SNe Ia (Maguire+, 2014)J/ApJ/821/57 : Photometry of the Type Ib/c SN2013ge (Drout+, 2016)J/ApJ/836/232 : Swift-UVOT obs. analysis of 29 SNe Ia (Brown+, 2017)J/A+A/604/L6 : EBLM J0555-57 photometry and RV (von Boetticher+, 2017)J/ApJ/869/56 : Updated calib. of the CSP-I SNe Ia sample (Burns+, 2018)J/ApJ/853/62 : Opt and NIR spectra and LCs of SN2016ija (Tartaglia+, 2018)J/ApJ/881/22 : BVI phot. of TypeII SN KSP-SN-2016kf (Afsariardchi+, 2019)J/ApJ/877/152 : UV to NIR light curves of type Ia SN 2017erp (Brown+, 2019)J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)J/A+A/627/A174 : Early light curve of SN 2013gy (Holmbo+, 2019)J/MNRAS/483/628 : SN Ia data using bolometric light curves (Scalzo+, 2019)J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 2019)J/ApJ/886/152 : ZTF early observations of Type Ia SNe. I. LCs (Yao+, 2019)J/ApJ/902/48 : ZTF early obs. of type Ia supernovae. III. (Bulla+, 2020)J/MNRAS/491/2902 : Sub-Chandrasekhar progenitors for Type Ia SNe (Flors+, 2020)J/ApJ/898/56 : UVOT, ZTF gri LCs & sp. of the SN Ia 2019yvq (Miller+, 2020)J/ApJ/902/47 : ZTF early obs. of type Ia SNe. II. Rise time (Miller+, 2020)J/MNRAS/493/1044 : Nebular spectra of 111 Type Ia supernovae (Tucker+, 2020)J/ApJ/922/186 : Keck/NIRES spectrum of type Ia SN 2020qxp (Hoeflich+, 2021)J/ApJ/910/151 : KMTNet BVi photometry of SNIa KSP-OT-201509b (Moon+, 2021)J/ApJ/914/50 : Opt. phot. and GMOS & NIRES sp. of SN2019yvq (Tucker+, 2021)J/ApJ/925/L22 : KMTNet BVI LCs & spectroscopy of KSP-OT-201701a (Lee+, 2022)J/ApJ/926/L25 : New LBT/MODS spectra of type Ia SN 2011fe (Tucker+, 2022)http://www.wiserep.org/ : Weizmann Interactive Supernova Data Repositoryhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/946/7https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/946/7http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/946/7https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/946/7https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/946/7http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/946/7GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/946/7/table1Nebular-phase magnitudes of SN 2018aozrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[58471.68/58658] Modified Julian Datedtime.epochdoubleBand[BVi] Photometric band usedmeta.code;instr.filtercharmag[19.19/22.1] Apparent magnitude in Band (1)magphot.magfloate_mag[0.03/0.4] Uncertainty in magmagstat.error;phot.magfloatJ/ApJ/946/7/table2Nebular-phase spectroscopy of SN 2018aozrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateYear of observation date (UT)stime.epochPhase[259.4/382.5] Observer frame days since the B-band maximum light (MJD 58221.41)dtime.intervalfloatTelTelescopemeta.id;instr.telcharInstInstrumentmeta.id;instrcharR[860/2000] Resolutionspect.resolutionintlam1[3200/5000] Lower limit of wavelength in {AA}0.1nmem.wl;stat.minintlam2[10000] Upper limit of wavelength in {AA}0.1nmem.wl;stat.maxintFile1Name of the spectra in subdirectory "sp" in ASCII format; column added by CDSmeta.id;meta.filecharFile2Name of the spectra in subdirectory "sp" in FITS format; column added by CDSmeta.id;meta.fitscharfitsDownload the FITS filemeta.ref.urlcharspInteractive spectrum plotmeta.ref.urlchar