J/A+A/677/A49ivo://CDS.VizieR/J/A+A/677/A49doi:10.26093/cds/vizier.36770049CDSIlyushin V.V.Muller H.S.P.Jorgensen J.K.Bauerecker S.Maul C.,Porohovoi R.Alekseev E.A.Dorovskaya O.Lewen F.Schlemmer S.,Lees R.M.2024-11-28T20:05:09Z2023-09-04T09:01:11ZCDS support team

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

cds-question@unistra.frinterstellar-mediumradio-spectroscopyspectroscopySolar-type prestellar cores and protostars display frequently large amounts of deuterated organic molecules and in particular high relative abundances of doubly and triply deuterated isotopologs. Recent findings on CHD_2_OH and CD_3_OH toward IRAS 16293-2422 suggest that even fully deuterated methanol, CD_3_OD, may be detectable as well. However, searches for CD_3_OD are hampered in particular by the lack of intensity information from a spectroscopic model. The objective of the present investigation is to develop a spectroscopic model of CD_3_OD in low-lying torsional states that is sufficiently accurate to facilitate searches for this isotopolog in space. We carried out a new measurement campaign for CD_3_OD involving two spectroscopic laboratories that covers the 34 GHz-1.1THz range. A torsion-rotation Hamiltonian model based on the rho-axis method was employed for our analysis. Our resulting model describes the ground and first excited torsional states of CD_3_OD well up to quantum numbers J<=51 and Ka<=23. We derived a line list for radio-astronomical observations from this model that 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_OD in data from the Protostellar Interferometric Line Survey of IRAS 16293-2422 obtained with the Atacama Large Millimeter/ submillimeter Array. While we found several emission features that can be attributed largely to CD_3_OD, their number is as yet insufficient to establish a clear detection. Nevertheless, the estimate of 2x10^15cm^-2^ derived for the CD3OD column density may be viewed as an upper limit that can be compared to column densities of CD_3_OH, CH_3_OD, and CH_3_OH. The comparison indicates that the CD_3_OD column density toward IRAS 16293-2422 is in line with the enhanced D/H ratios observed for multiply deuterated complex organic molecules.2023A&A...677A..49Ihttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/677/A49CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/677/A49https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/677/A49http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/677/A49https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/677/A49https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/677/A49http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/677/A49GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapMillimeterdefaultJ/A+A/677/A49/tableb1Assigned microwave transitions of the CD_3_OD spectrum used in the analysisrecnoRecord 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.mol.qn;stat.maxintJ'Upper J quantum numberinstr.det.qe;stat.maxintKa'Upper Ka quantum numberphys.mol.qn;stat.maxintKc'Upper Kc quantum numberphys.mol.qn;stat.maxintSym"Lower level symmetry in the G6 groupphys.atmolcharm"Lower free rotor torsional quantum numberphys.mol.qn;stat.minintJ"Lower J quantum numberinstr.det.qe;stat.minintKa"Lower Ka quantum numberphys.mol.qn;stat.minintKc"Lower Kc quantum numberphys.mol.qn;stat.minintFreqObserved transition frequencyMHzem.freqdoubleuncUncertainty of measurementMHzstat.errorfloatO-CResiduals from the fitMHzstat.fit.residualdoubleCmntSource of data (1)meta.bibcharJ/A+A/677/A49/tableb2Assigned FIR transitions of the CD_3_OD spectrum used in the analysisrecnoRecord 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.mol.qn;stat.maxintJ'Upper J quantum numberinstr.det.qe;stat.maxintKa'Upper Ka quantum numberphys.mol.qn;stat.maxintKc'Upper Kc quantum numberphys.mol.qn;stat.maxintSym"Lower level symmetry in the G6 groupphys.atmolcharm"Lower free rotor torsional quantum numberphys.mol.qn;stat.minintJ"Lower J quantum numberinstr.det.qe;stat.minintKa"Lower Ka quantum numberphys.mol.qn;stat.minintKc"Lower Kc quantum numberphys.mol.qn;stat.minintFreqObserved transition frequencycm**-1em.freqdoubleuncUncertainty of measurementcm**-1stat.errorfloatO-CResiduals from the fitcm**-1stat.fit.residualdoubleJ/A+A/677/A49/tableb3Predicted transition frequencies of the ground and first excited torsional states of CD_3_OD in the frequency range from 1GHz up to 1.33THzrecnoRecord 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.mol.qn;stat.maxintJ'Upper J quantum numberinstr.det.qe;stat.maxintKa'Upper Ka quantum numberphys.mol.qn;stat.maxintKc'Upper Kc quantum numberphys.mol.qn;stat.maxintSym"Lower level symmetry in the G6 groupphys.atmolcharm"Lower free rotor torsional quantum numberphys.mol.qn;stat.minintJ"Lower J quantum numberinstr.det.qe;stat.minintKa"Lower Ka quantum numberphys.mol.qn;stat.minintKc"Lower Kc quantum numberphys.mol.qn;stat.minintFreqPredicted transition frequencyMHzem.freqdoubleuncPredicted uncertainty of transition frequencyMHzstat.errordoubleEloThe 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/677/A49/tableb4Torsion-rotation part Qrt(T) of the total internal partition function Q(T)=Qv(T)*Qrt(T), calculated for CD3OD from first principlesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTTemperatureKphys.temperaturefloatQrtTorsion-rotation part of the partition functionphys.atmoldouble