J/A+A/658/A127ivo://CDS.VizieR/J/A+A/658/A127doi:10.26093/cds/vizier.36580127CDSIlyushin V.V.Muller H.S.P.Jorgensen J.K.Bauerecker S.Maul C.,Bakhmat Y.Alekseev E.A.Dorovskaya O.Vlasenko S.Lewen F.,Schlemmer S.Berezkin K.Lees R.M.2022-08-25T12:50:11Z2022-02-10T08:32:38ZCDS support team

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

cds-question@unistra.frinterstellar-mediumradio-spectroscopyspectroscopySolar-type protostars have been shown to harbor highly deuterated complex organics as for example witnessed by the high relative abundances of doubly and triply deuterated isotopologs. While this degree of deuteration may provide important clues to the formation of these species, spectroscopic information on multiply deuterated isotopologs is often insufficient. In particular, searches for triply deuterated methanol, CD_3_OH, are hampered to a large extent by the lack of intensity information from a spectroscopic model. The aim of the present study is to develop a spectroscopic model of CD_3_OH in low-lying torsional states sufficiently accurate to facilitate further searches for CD_3_OH in space. We have performed a new measurement campaign for CD_3_OH involving three spectroscopic laboratories which covers the 34GHz-1.1THz and the 20-900cm^-1^ ranges. The analysis was perfomed using the rho-axis-method torsion- rotation Hamiltonian model. We determined a model that describes the ground and first excited torsional states of CD_3_OH up to quantum numbers J<=55 and K<=23, and derived a line list for radio-astronomical observations. The resulting line list is accurate up to at least 1.1THz and should be sufficient for all types of radio-astronomical searches for this methanol isotopolog. This line list was used to search for CD_3_OH in data from the Protostellar Interferometric Line Survey of IRAS 16293-2422 using the Atacama Large Millimeter/submillimeter Array. CD_3_OH is securely detected in the data with a large number of clearly separated and well-reproduced lines. We detected not only lines belonging to the ground torsional state, but also several belonging to the first excited torsional state. The derived column density of CD_3_OH and abundance relative to non-deuterated isotopolog confirm the significant enhancement of this multiply deuterated variant. This is in line with other observations of multiply deuterated complex organic molecules and may serve as an important constraint on models for their formation.2022A&A...658A.127Ihttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/658/A127CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/658/A127https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/658/A127http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/658/A127https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/658/A127https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/658/A127http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/658/A127GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapMillimeterdefaultJ/A+A/658/A127/tablea1Assigned microwave transitions of the CD_3_OH spectrum used in the analysisSym'Upper level symmetry in the G6 groupphys.atmolcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintm'Upper free rotor torsional quantum numberphys.atmol.qn;stat.maxintJ'Upper J quantum numberinstr.det.qe;stat.maxintKa'Upper Ka quantum numberphys.atmol.qn;stat.maxintKc'Upper Kc quantum numberphys.atmol.qn;stat.maxintSym"Lower level symmetry in the G6 groupphys.atmolcharm"Lower free rotor torsional quantum numberphys.atmol.qn;stat.minintJ"Lower J quantum numberinstr.det.qe;stat.minintKa"Lower Ka quantum numberphys.atmol.qn;stat.minintKc"Lower Kc quantum numberphys.atmol.qn;stat.minintFreqObserved transition frequencyMHzem.freqdoubleuncUncertainty of measurementMHzstat.errorfloatO-CResiduals from the fitMHzstat.fit.residualdoubleCmntSource of datameta.bibcharJ/A+A/658/A127/tablea2Assigned FIR transitions of the CD_3_OH spectrum used in the analysisKc'Upper Kc quantum numberphys.atmol.qn;stat.maxintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSym'Upper level symmetry in the G6 groupphys.atmolcharm'Upper free rotor torsional quantum numberphys.atmol.qn;stat.maxintJ'Upper J quantum numberinstr.det.qe;stat.maxintKa'Upper Ka quantum numberphys.atmol.qn;stat.maxintSym"Lower level symmetry in the G6 groupphys.atmolcharm"Lower free rotor torsional quantum numberphys.atmol.qn;stat.minintJ"Lower J quantum numberinstr.det.qe;stat.minintKa"Lower Ka quantum numberphys.atmol.qn;stat.minintKc"Lower Kc quantum numberphys.atmol.qn;stat.minintFreqObserved transition frequencycm**-1em.freqdoubleuncUncertainty of measurementcm**-1stat.errorfloatO-CResiduals from the fitcm**-1stat.fit.residualdoubleJ/A+A/658/A127/tablea3Predicted transition frequencies of the ground and first excited torsional states of CD_3_OH in the frequency range from 1GHz up to 1.3THzrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSym'Upper level symmetry in the G6 groupphys.atmolcharm'Upper free rotor torsional quantum numberphys.atmol.qn;stat.maxintJ'Upper J quantum numberinstr.det.qe;stat.maxintKa'Upper Ka quantum numberphys.atmol.qn;stat.maxintKc'Upper Kc quantum numberphys.atmol.qn;stat.maxintSym"Lower level symmetry in the G6 groupphys.atmolcharm"Lower free rotor torsional quantum numberphys.atmol.qn;stat.minintJ"Lower J quantum numberinstr.det.qe;stat.minintKa"Lower Ka quantum numberphys.atmol.qn;stat.minintKc"Lower Kc quantum numberphys.atmol.qn;stat.minintFreqPredicted transition frequencyMHzem.freq;phys.atmol.transitiondoubleuncPredicted uncertainty of transition frequencyMHzstat.error;em.freq;phys.atmol.transitiondoubleEloThe energy of the lower statecm**-1phys.energy;phys.atmol.leveldoubleSm2Dipole moment squared multiplied by the transition linestrength and nuclear spin statistical weightD**2stat.weight;phys.atmol.sWeight.nuclear;phys.atmol.transitiondoubleJ/A+A/658/A127/tablea4Torsion-rotation part Qrt(T) of the total internal partition function Q(T)=Qv(T)*Qrt(T), calculated for CD_3_OH from first principles (corrected version, 20-Mar-2022)QrtTorsion-rotation part of the partition functionphys.atmoldoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTTemperatureKphys.temperaturefloat