J/A+A/640/A98ivo://CDS.VizieR/J/A+A/640/A98doi:10.26093/cds/vizier.36400098CDSBizzocchi L.Prudenzano D.Rivilla V.M.Pietropolli-Charmet A.,Giuliano B.M.Caselli P.Martin-Pintado J.Jimenez-Serra I.Martin S.,Requena-Torres M.A.Rico-Villas F.Zeng S.Guillemin J.-C.2020-11-26T08:40:14Z2020-08-20T08:11:13ZCDS support team

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

cds-question@unistra.fratomic-physicsSmall imines containing up to three carbon atoms are present in the interstellar medium. As alkynyl compounds are abundant in this medium, propargylimine (2-propyn-1-imine, HC=C-CH=NH) thus represents a promising candidate for a new interstellar detection. The goal of the present work is to perform a comprehensive laboratory investigation of the rotational spectrum of propargylimine in its ground vibrational state in order to obtain a highly precise set of rest-frequencies and to search it in space. The rotational spectra of E and Z geometrical isomers of propargylimine have been recorded in laboratory in the 83-500GHz frequency interval. The measurements have been performed using a source-modulation millimetre-wave spectrometer equipped with a pyrolysis system for the production of unstable species. High-level ab initio calculations were performed to assist the analysis and to obtain reliable estimates for an extended set of spectroscopic quantities. We have searched for propargylimine at 3 and 2mm in the spectral survey of the quiescent giant molecular cloud G+0.693-0.027 located in the "Central Molecular Zone", close to the Galactic Centre. About 1000 rotational transitions have been recorded for the E- and Z-propargylimine, in the laboratory. These new data have enabled the determination of a very accurate set of spectroscopic parameters including rotational, quartic and sextic centrifugal distortion constants. The improved spectral data allow us to perform a successful search for this new imine in the G+0.693-0.027 molecular cloud. Eighteen lines of Z-propargylimine have been detected at level >2.5*sigma, resulting in a column density estimate of N=(0.24+/-0.02)x10^-14^cm^-2^. An upper limit was retrieved for the higher-energy E isomer, which was not detected in the data. The fractional abundance (w.r.t. H_2_) derived for Z-propargylimine is 1.8x10^-10^. We discuss the possible formation routes by comparing the derived abundance with those measured in the source for possible chemical precursors.2020A&A...640A..98Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/640/A98CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/640/A98https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/640/A98http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/640/A98https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/640/A98https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/640/A98http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/640/A98GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/640/A98/tablee1Assignments, measured line positions and least-squares residuals for the analysed transitions of Z-PGIM with hyperfine structurerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ'Upper state Jphys.molintKa'Upper state Kaphys.molintKc'Upper state Kcphys.molintF'Upper state Fphys.molintJLower state Jphys.molintKaLower state Kaphys.molintKcLower state Kcphys.molintFLower state Fphys.molintObs? Measured line position (1)MHzem.freqdoublenullableO-C? Least-squares residual (1)MHzstat.fit.residualdoublenullableWeightBlend? Relative weight in a line blendstat.weightfloatnullableJ/A+A/640/A98/tablee2Assignments, measured line positions and least-squares residuals for the analysed transitions of Z-PGIM without hyperfine structurerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ'Upper state Jphys.molintKa'Upper state Kaphys.molintKc'Upper state Kcphys.molintJLower state Jphys.molintKaLower state Kaphys.molintKcLower state Kcphys.molintObs? Measured line position (1)MHzem.freqdoublenullableO-C? Least-squares residual (1)MHzstat.fit.residualdoublenullableWeightBlend? Relative weight in a line blendstat.weightfloatnullableRefReference (2)meta.ref;pos.framecharJ/A+A/640/A98/tablee3Assignments, measured line positions and least-squares residuals for the analysed transitions of E-PGIM with hyperfine structureJLower state Jphys.molintKc'Upper state Kcphys.molintF'Upper state Fphys.molintKaLower state Kaphys.molintKcLower state Kcphys.molintFLower state Fphys.molintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ'Upper state Jphys.molintKa'Upper state Kaphys.molintObs? Measured line position (1)MHzem.freqdoublenullableO-C? Least-squares residual (1)MHzstat.fit.residualdoublenullableWeightBlend? Relative weight in a line blendstat.weightfloatnullableJ/A+A/640/A98/tablee4Assignments, measured line positions and least-squares residuals for the analysed transitions of E-PGIM without hyperfine structureKaLower state Kaphys.molintKcLower state Kcphys.molintJ'Upper state Jphys.molintKa'Upper state Kaphys.molintKc'Upper state Kcphys.molintJLower state Jphys.molintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs? Measured line position (1)MHzem.freqdoublenullableO-C? Least-squares residual (1)MHzstat.fit.residualdoublenullableWeightBlend? Relative weight in a line blendstat.weightfloatnullableRefReference (2)meta.ref;pos.framechar