J/ApJ/914/50ivo://CDS.VizieR/J/ApJ/914/50doi:10.26093/cds/vizier.19140050CDSTucker M.A.Ashall C.Shappee B.J.Vallely P.J.Kochanek C.S.,Huber M.E.Anand G.S.Keane J.V.Hsiao E.Y.Holoien T.W.-S.2023-01-18T06:16:54Z2022-12-28T15:34:25ZCDS support team

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

cds-question@unistra.frsupernovaephotometryvisible-astronomyspectroscopyinfrared-astronomyWe present new photometric and spectroscopic observations of SN2019yvq, a Type Ia supernova (SN Ia) exhibiting several peculiar properties including an excess of UV/optical flux within days of explosion, a high Si ii velocity, and a low peak luminosity. Photometry near the time of first light places new constraints on the rapid rise of the UV/optical flux excess. A near-infrared spectrum at +173 days after maximum light places strict limits on the presence of H or He emission, effectively excluding the presence of a nearby nondegenerate star at the time of explosion. New optical spectra, acquired at +128 and +150 days after maximum light, confirm the presence of [CaII]{lambda}7300 and persistent CaII NIR triplet emission as SN 2019yvq transitions into the nebular phase. The lack of [OI]{lambda}6300 emission disfavors the violent merger of two C/O white dwarfs (WDs) but the merger of a C/O WD with a He WD cannot be excluded. We compare our findings with several models in the literature postulated to explain the early flux excess including double-detonation explosions, ^56^Ni mixing into the outer ejecta during ignition, and interaction with H- and He-deficient circumstellar material. Each model may be able to explain both the early flux excess and the nebular [CaII] emission, but none of the models can reconcile the high photospheric velocities with the low peak luminosity without introducing new discrepancies.2021ApJ...914...50Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/914/50CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)J/MNRAS/425/1789 : Berkeley supernova Ia program. I. (Silverman+, 2012)J/A+A/554/A27 : 2011fe spectrophotometric time series (Pereira+, 2013)J/ApJ/795/142 : Defining phot. peculiar SNe Ia (Gonzalez-Gaitan+, 2014)J/MNRAS/444/3258 : Velocities and EW of PTF SNe Ia (Maguire+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/MNRAS/451/1973 : Type Ia supernovae igh-velocity features (Silverman+, 2015)J/AJ/152/50 : Cosmicflows-3 catalog (CF3) (Tully+, 2016)J/ApJ/843/16 : Galaxy groups within 3500km/s (Kourkchi+, 2017)J/AJ/154/211 : CSP (DR3): photometry of low-z SNe Ia (Krisciunas+, 2017)J/A+A/611/A58 : SN 2007on and SN 2011iv light curves (Gall+, 2018)J/A+A/630/A76 : SN2016hnk photometry and spectroscopy (Galbany+, 2019)J/ApJ/883/111 : UV-Opt LCs of ASASSN-19bt detected by TESS (Holoien+, 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/ApJ/898/56 : UVOT, ZTF gri LCs & sp. of the SN Ia 2019yvq (Miller+, 2020)J/ApJ/908/51 : TESS early LCs of type Ia Supernovae (Fausnaugh+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/914/50https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/914/50http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/914/50https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/914/50https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/914/50http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/914/50GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/914/50/table2New ASAS-SN and TESS photometry of SN 2019yvqrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceObservation source (1)meta.id;instrcharMJD[58812.47/58925.97] Modified Julian Datedtime.epochdoubleFlux[-0.026/3.99] Observed flux densitymJyphot.flux.densityfloate_Flux[0.014/0.13] Uncertainty in FluxmJystat.error;phot.fluxfloatJ/ApJ/914/50/fig4Late-phase and nebular GMOS spectra of SN 2019yvqrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[128/150] Observation epoch; days after time of maximum lightdtime.epoch;obsintlambda[4550/9200] Wavelength in Angstroms0.1nmem.wlintFlux[7.97e-21/2.5e-16] Flux in erg/s/cm^2^/AngstromscW.m**-2.nm**-1phot.fluxdoublee_Flux[2.8e-21/1.5e-16] Uncertainty in FluxcW.m**-2.nm**-1stat.error;phot.fluxdoubleJ/ApJ/914/50/fig5NIRES spectrum of SN 2019yvq at +173 days after maximum light (MJD59038.263)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintOrder[3/7] NIRES order numbermeta.id;meta.mainintlambda[0.8/2.5] Wavelengthumem.wldoubleFlux[-2.62e-12/1.82e-13] Relative flux in erg/s/cm^2^/AngstromscW.m**-2.nm**-1phot.fluxdouble