J/ApJ/922/L10ivo://CDS.VizieR/J/ApJ/922/L10doi:10.26093/cds/vizier.19229010CDSWoodward C.E.Banerjee D.P.K.Geballe T.R.Page K.L.Starrfield S.,Wagner R.M.2023-08-25T12:49:25Z2023-05-04T10:31:10ZCDS support team

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

cds-question@unistra.frnovaeinfrared-astronomyspectroscopyWe present near-infrared spectroscopy of Nova Herculis 2021 (V1674 Her), obtained over the first 70 days of its evolution. This fastest nova on record displays a rich emission line spectrum, including strong coronal line emission with complex structures. The hydrogen line fluxes, combined with a distance of 4.7_-1.0_^+1.3^kpc, give an upper limit to the hydrogen ejected mass of M_ej_=1.4_-1.2_^+0.8^x10^-3^M_{sun}_. The coronal lines appeared at day 11.5, the earliest onset yet observed for any classical nova, before there was an obvious source of ionizing radiation. We argue that the gas cannot be photoionized, at least in the earliest phase, and must be shocked. Its temperature is estimated to be 105.57+/-0.05K on day 11.5. Tentative analysis indicates a solar abundance of aluminum and an underabundance of calcium, relative to silicon, with respect to solar values in the ejecta. Further, we show that the vexing problem of whether collisional ionization or photoionization is responsible for coronal emission in classical novae can be resolved by correlating the temporal sequence in which the X-ray supersoft phase and the near-infrared coronal line emission appear.2021ApJ...922L..10Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/922/L10CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-)B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)VI/64 : Recombination line intensities for hydrogenic ions (Storey+ 1995)J/A+A/453/635 : Modelling Galactic Interstellar Extinction (Marshall+, 2006)J/AJ/140/34 : Classification of nova light curves (Strope+, 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/922/L10https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/922/L10http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/922/L10https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/922/L10https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/922/L10http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/922/L10GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/ApJ/922/L10/table1*Observational log V1674 HerrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsYear of the observationstime.epochMJD[383.544/446.284] Modified Julian Date; MJD-59000dtime.epochfloatDay[5.64/68.32] Day relative to t_0_=June 12.96 UT (MJD59377.96)dtime.intervalfloatModeSpeX mode (1)instr.setupcharf_ModeFlag on spectra (2)meta.codecharExp[356/1977] Total on-source integration time on the novastime.epochintAirmass[1.01/1.65] Average airmassobs.airMassfloatStdNameStandard HD namemeta.idcharFileNameName of the ASCII file in subdirectory "sp"; column added by CDSmeta.id;meta.filecharspInteractive plot of the spectrummeta.ref.urlchar