J/ApJ/958/173ivo://CDS.VizieR/J/ApJ/958/173doi:10.26093/cds/vizier/ba-xy-5dCDSSiebert M.R.Foley R.J.Zenati Y.Dimitriadis G.Schmidt E.Yang G.,Davis K.W.Taggart K.Rojas-Bravo C.2026-03-02T20:03:05Z2026-02-23T10:05:04ZCDS support team

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

cds-question@unistra.frsupernovaevisible-astronomyspectroscopyWe present nebular spectroscopy of SN 2020hvf, a Type Ia supernova (SNIa) with an early bump in its light curve. SN 2020hvf shares many spectroscopic and photometric similarities to the carbon-rich high-luminosity "03fg-like" SNe Ia. At >240 days after peak brightness, we detect unambiguous emission from [CaII] {lambda}{lambda}7291,7324, which is rarely observed in normal SNe Ia and only seen in peculiar subclasses. SN 2020hvf displays "sawtooth" emission profiles near 7300{AA} that cannot be explained with single symmetric velocity components of [FeII], [NiII], and [CaII], indicating an asymmetric explosion. The broad [CaII] emission is best modeled by two velocity components offset by 1220km/s, which could be caused by ejecta associated with each star in the progenitor system, separated by their orbital velocity. For the first time in an SN Ia, we identify narrow (FWHM=180{\pm}40km/s) [CaII] emission, which we associate with a wind from a surviving, puffed-up companion star. Few published spectra have sufficient resolution and the signal-to-noise ratio necessary to detect similar narrow [CaII] emission; however, we have detected similar line profiles in other 03fg-like SNe Ia. The extremely narrow velocity width of [CaII] has only otherwise been observed in SNe Iax at late times. Since this event likely had a double-degenerate "super-Chandrasekhar" mass progenitor system, we suggest that a single white dwarf (WD) was fully disrupted and a wind from a surviving companion WD is producing the observed narrow emission. It is unclear whether this unique progenitor and explosion scenario can explain the diversity of 03fg-like SNe Ia, potentially indicating that multiple progenitor channels contribute to this subclass.2023ApJ...958..173Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/958/173CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJS/190/418 : Light curves for 165 SNe (Ganeshalingam+, 2010)J/ApJ/742/89 : Relations between spectra & colors of SNe Ia (Foley+, 2011)J/MNRAS/410/585 : SN 2009dc BVRI light curves (Silverman+, 2011)J/MNRAS/425/1789 : Berkeley supernova Ia program. I. (Silverman+, 2012)J/ApJ/826/56 : HST/WFC3 obs. of Cepheids in SN Ia host gal. (Riess+, 2016)J/A+A/595/A118 : NIBLES. I. The Nancay HI survey (van Driel+, 2016)J/ApJ/843/16 : Galaxy groups within 3500km/s (Kourkchi+, 2017)J/ApJ/850/207 : Action dynamics of the Local Supercluster (Shaya+, 2017)J/A+A/620/A141 : Physical properties of AM CVn stars (Ramsay+, 2018)J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)J/A+A/630/A76 : SN2016hnk photometry and spectroscopy (Galbany+, 2019)J/ApJS/244/24 : A z=0 Multiwavelength Gal. Synth. (z0MGS). I. (Leroy+, 2019)J/ApJ/900/140 : CSP-II: sp. obs. of the SN Ia LSQ14fmg (Hsiao+, 2020)J/ApJ/898/166 : UV to NIR obs. of SN 2019ehk (Jacobson-Galan+, 2020)J/ApJ/898/56 : UVOT, ZTF gri LCs & sp. of the SN Ia 2019yvq (Miller+, 2020)J/MNRAS/493/1044 : Nebular spectra of 111 Type Ia supernovae (Tucker+, 2020)J/ApJ/923/L8 : Follow-up phot. & sp. of SNIa 2020hvf (Jiang+, 2021)J/ApJ/914/50 : Opt. phot. and GMOS & NIRES sp. of SN2019yvq (Tucker+, 2021)J/ApJ/927/78 : Phot. & sp. follow-up of SNIa SN2020esm (Dimitriadis+, 2022)J/ApJ/943/L20 : Phot. obs. of SN 2022ilv and SN 2020hvf (Srivastav+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/958/173https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/958/173http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/958/173https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/958/173https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/958/173http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/958/173GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/958/173/listList of spectra presented in Data behind Figure 1; table added by CDSrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFileName of the ASCII file in subdirectory "sp"meta.id;meta.filecharDays[240/332] Days after peak brightnessdtime.intervalintInstInstrument ("KAST"; "LRIS"; "LRIS (blue)" or "LRIS (red)")meta.id;instrcharDateObservation date (UT)stime.epoch;obsnullablespInteractive spectrum plotmeta.ref.urlchar