J/A+A/587/L4ivo://CDS.VizieR/J/A+A/587/L4doi:10.26093/cds/vizier.35879004CDSCernicharo J.Kisiel Z.Tercero B.Kolesnikova L.Medvedev I.R.,Lopez A.Fortman S.Winnewisser M.de Lucia F.C.Alonso J.L.,Guillemin J.-C.2016-02-25T07:34:26Z2016-02-25T08:25:02ZCDS support team

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

cds-question@unistra.frinterstellar-mediumradio-astronomyspectroscopyThe recent analysis of the composition of the frozen surface of comet 67P/Churyumov-Gerasimenko has revealed a significant number of complex organic molecules. Methyl isocyanate (CH_3_NCO) is one of the more abundant species detected on the comet surface. In this work we report extensive characterization of its rotational spectrum resulting in a list of 1269 confidently assigned laboratory lines and its detection in space towards the Orion clouds where 399 lines of the molecule have been unambiguously identified. We find that the limited mm-wave laboratory data reported prior to our work require some revision. The abundance of CH_3_NCO in Orion is only a factor of ten below those of HNCO and CH_3_CN. Unlike the molecular abundances in the coma of comets, which correlate with those of warm molecular clouds, molecular abundances in the gas phase in Orion are only weakly correlated with those measured on the comet surface. We also compare our abundances wit those derived recently for this molecule towards Sgr B2 (Halfen et al., 2015ApJ...812L...5H). A more accurate abundance of CH_3_NCO is provided for this cloud based on our extensive laboratory work.2016A&A...587L...4Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/587/L4CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/587/L4https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/587/L4http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/587/L4https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/587/L4https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/587/L4http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/587/L4GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadioOpticaldefaultJ/A+A/587/L4/tablea6Line list for CH_3_NCOrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFreqFrequencyMHzem.freqdoublee_FreqError on frequencyMHzstat.errorfloatLog(Int)Base 10 logarithm of the integrated intensity in units of nm2 MHz at 300Kspect.line.intensityfloatDRDegrees of freedom in the rotational partition functionstat.fit.dofintElowEnergy of the lower levelcm**-1phys.energy;phys.atmol.leveldoubleguppUpper state degeneracyphys.electron.degenintTAGSpecies tag or molecular identifiermeta.codeintQNFMTFormat of the quantum numbersphys.atmol.qnintQN0aQuantum numbers for the upper statephys.atmol.qnintQN0bQuantum numbers for the upper statephys.atmol.qnintQN0cQuantum numbers for the upper statephys.atmol.qnintQN0dQuantum numbers for the upper statephys.atmol.qnintQN0e? Quantum numbers for the upper statephys.atmol.qnintnullableQN1aQuantum numbers for the lower statephys.atmol.qnintQN1bQuantum numbers for the lower statephys.atmol.qnintQN1cQuantum numbers for the lower statephys.atmol.qnintQN1dQuantum numbers for the lower statephys.atmol.qnintQN1e? Quantum numbers for the lower statephys.atmol.qnintnullableSeqSequencemeta.notechar