J/A+A/676/L5ivo://CDS.VizieR/J/A+A/676/L5doi:10.26093/cds/vizier.36769005CDSCabezas C.Tang J.Agundez M.Seiki K.Sumiyoshi Y.Ohshima Y.,Tercero B.Marcelino N.Fuentetaja R.de Vicente P.Endo Y.,Cernicharo J.2024-11-28T20:04:59Z2023-07-31T07:54:58ZCDS support team

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

cds-question@unistra.fratomic-physicsWe report the first laboratory and interstellar detection of the alpha-cyano vinyl radical (H_2_CCCN). This species was produced in the laboratory by an electric discharge of a gas mixture of vinyl cyanide, CH_2_CHCN, and Ne, and its rotational spectrum was characterized using a Balle-Flygare narrowband-type Fourier-transform microwave spectrometer operating in the frequency region of 8-40GHz. The observed spectrum shows a complex structure due to tunneling splittings between two torsional sublevels of the ground vibronic state, 0+ and 0-, derived from a large-amplitude inversion motion. In addition, the presence of two equivalent hydrogen nuclei makes necessary to discern between ortho- and para-H_2_CCCN. A least squares analysis reproduces the observed transition frequencies with a standard deviation of ca. 3kHz. Using the laboratory predictions, this radical is detected in the cold dark cloud TMC-1 using the Yebes 40m telescope and the QUIJOTE line survey. The 404-303 and 505-404 rotational transitions, composed of several hyperfine components, were observed in the 31.0-50.4GHz range. Adopting a rotational temperature of 6K we derive a column density of (1.4+/-0.2)*10^-11^cm^-2^ and (1.1+/-0.2)*10^-11^cm^-2^ for ortho-H_2_CCCN and para-H_2_CCCN, respectively. The reactions C + CH_3_CN, and perhaps also N + CH_2_CCH, emerge as the most likely routes to H_2_CCCN in TMC-1.2023A&A...676L...5Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/676/L5CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/676/L5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/676/L5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/676/L5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/676/L5https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/676/L5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/676/L5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/676/L5/tablea3Predicted frequencies for ortho-H_2_C_3_NFreqFrequencyMHzem.freqdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUncUncertaintyMHzstat.error;em.freqfloatlogIntBase 10 logarithm of the integrated intensitylog(nm**2.MHz)spect.line.intensitydoubleDOFDegrees of freedom of rotation partition functioncm**-1stat.fit.dofintElowLower state energycm**-1phys.energydoublegupUpper state degeneracyphys.electron.degenintTAGMolecular identifiermeta.id;meta.maincharN'Quantum number N for upper levelphys.mol.qnintKa'Quantum number Ka for upper levelphys.mol.qnintKc'Quantum number Kc for upper levelphys.mol.qnintTSP'TSP aggregate spin number for upper levelphys.mol.qnintF'Quantum number F for upper levelphys.mol.qnintN"Quantum number N for lower levelphys.mol.qnintKa"Quantum number Ka for lower levelphys.mol.qnintKc"Quantum number Kc for lower levelphys.mol.qnintTSP"TSP aggregate spin number for lower levelphys.mol.qnintF"Quantum number F for lower levelphys.mol.qnintJ/A+A/676/L5/tablea4Predicted frequencies for para-H_2_C_3_NFreqFrequencyMHzem.freqdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUncUncertaintyMHzstat.error;em.freqfloatlogIntBase 10 logarithm of the integrated intensitylog(nm**2.MHz)spect.line.intensitydoubleDOFDegrees of freedom of rotation partition functioncm**-1stat.fit.dofintElowLower state energycm**-1phys.energydoublegupUpper state degeneracyphys.electron.degenintTAGMolecular identifiermeta.id;meta.maincharN'Quantum number N for upper levelphys.mol.qnintKa'Quantum number Ka for upper levelphys.mol.qnintKc'Quantum number Kc for upper levelphys.mol.qnintTSP'TSP aggregate spin number for upper levelphys.mol.qnintF'Quantum number F for upper levelphys.mol.qnintN"Quantum number N for lower levelphys.mol.qnintKa"Quantum number Ka for lower levelphys.mol.qnintKc"Quantum number Kc for lower levelphys.mol.qnintTSP"TSP aggregate spin number for lower levelphys.mol.qnintF"Quantum number F for lower levelphys.mol.qnint