J/A+A/646/A22ivo://CDS.VizieR/J/A+A/646/A22doi:10.26093/cds/vizier.36460022CDSYang S.Sollerman J.Chen T.-W.Kool E.C.Lunnan R.Schulze S.,Strotjohann N.Horesh A.Kasliwal M.Kupfer T.Mahabal A.A.Masci F.J.,Nugent P.Perley D.A.Riddle R.Rusholme B.Sharma Y.2021-10-05T13:03:53Z2021-02-02T08:01:26ZCDS support team

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

cds-question@unistra.frsupernovaeinfrared-photometryvisible-astronomyWide-band photometryultraviolet-photometryspectroscopyWe present observations of SN 2020faa. This Type II supernova displays a luminous lightcurve that started to rebrighten from an initial decline. We investigate this in relation to the famous supernova iPTF14hls, which received a great deal of attention and multiple interpretations in the literature, but whose nature and source of energy still remain unknown. We demonstrate the great similarity between SN 2020faa and iPTF14hls during the first 6 months, and use this comparison to forecast the evolution of SN 2020faa and to reflect on the less well observed early evolution of iPTF14hls. We present and analyse our observational data, consisting mainly of optical lightcurves from the Zwicky Transient Facility in the gri bands and of a sequence of optical spectra. We construct colour curves and a bolometric lightcurve, and we compare ejecta-velocity and black-body radius evolutions for the two supernovae and for more typical Type II supernovae. The lightcurves show a great similarity with those of iPTF14hls over the first 6 months in luminosity, timescale, and colour. In addition, the spectral evolution of SN 2020faa is that of a Type II supernova, although it probes earlier epochs than those available for iPTF14hls. The similar lightcurve behaviour is suggestive of SN 2020faa being a new iPTF14hls. We present these observations now to advocate follow-up observations, since most of the more striking evolution of supernova iPTF14hls came later, with lightcurve undulations and a spectacular longevity. On the other hand, for SN 2020faa we have better constraints on the explosion epoch than we had for iPTF14hls, and we have been able to spectroscopically monitor it from earlier phases than was done for the more famous sibling.2021A&A...646A..22Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/646/A22CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/646/A22https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/646/A22http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/646/A22https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/646/A22https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/646/A22http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/646/A22GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapUVOpticalInfrareddefaultJ/A+A/646/A22/photPhotometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation Datetime.epoch;obsnullableJDJulian Datedtime.epochdoubleFilter[1/9] Filter (1)meta.id;instr.filterintMAG? Absolute magnitude in Filter (2)magphys.magAbsfloatnullablemag? Apparent magnitude in Filtermagphot.magfloatnullablee_mag? Magnitude Errormagstat.error;phot.magfloatnullablelimmag? Limiting Magnitude in Filtermagphot.magfloatnullableInstrInstrumentmeta.id;instrcharIssubIf it's host subtracted magnitudemeta.codecharJ/A+A/646/A22/spe1Spectrum taken by P60+SEDM on 2020-03-31recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe2Spectrum taken by LT+SPRAT on 2020-04-05recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe3Spectrum taken by P60+SEDM on 2020-06-01recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe4Spectrum taken by P60+SEDM on 2020-06-21recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe5Spectrum taken by NOT+ALFOSC on 2020-07-02recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe6Spectrum taken by NOT+ALFOSC on 2020-07-24recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe7Spectrum taken by P60+SEDM on 2020-07-26recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe8Spectrum taken by P60+SEDM on 2020-08-01recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe9Spectrum taken by P60+SEDM on 2020-08-11recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe10Spectrum taken by NOT+ALFOSC on 2020-08-15recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe11Spectrum taken by P60+SEDM on 2020-08-21recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe12Spectrum taken by P60+SEDM on 2020-08-24recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe13Spectrum taken by NOT+ALFOSC on 2020-08-30recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdoubleJ/A+A/646/A22/spe14Spectrum taken by P60+SEDM on 2020-09-06recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFluxFlux (1)phot.fluxdouble