J/A+A/702/A23ivo://CDS.VizieR/J/A+A/702/A23doi:10.26093/cds/vizier/bc-ny/lcdCDSFuentetaja R.Cabezas C.Endo Y.Agundez M.Godard Palluet A.Lique F.,Tercero B.Marcelino N.de Vicente P.Cernicharo J.2026-08-03T06:58:08Z2025-09-30T09:48:01ZCDS support team

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

cds-question@unistra.frinterstellar-mediumspectroscopyradio-astronomyWe performed a detailed analysis of the isotopologues with ^13^C, ^34^S, ^33^S, and ^36^S of the sulphur-bearing molecules CS, CCS, CCCS, HCS+, HCCS+, and H_2_CS towards the starless core TMC-1 using the QUIJOTE line survey. The observations were obtained with the Yebes 40m radio telescope, and the sensitivity of the data varied between 0.08 and 0.2mK in the 31-50GHz range. Observations with the IRAM 30m radio telescope of the most abundant isotopologues of these species are also presented and used to estimate volume densities and to constrain the excitation conditions of these molecules. Among these species, we report the first detection in space of C^13^C^34^S, CC^33^S, CCC^33^S, HC^33^S+, and HCC^34^S+. C^36^S is also detected for the first time in a cold starless object. These data were complemented with sensitive maps that provide the spatial distribution of most of these species. Using the available collisional rate coefficients for each species, we modeled the observed line intensities using the large velocity gradient method for the radiative transfer. The results allowed us to report the most complete analysis of the column densities of the CnS family and to compare the abundance ratios of all detected isotopologues. Adopting a kinetic temperature for TMC-1 of 9K, we found that n(H_2_)=0.9-1.5x10^4^cm^-3^ can explain the observed decline in intensity with increasing rotational levels J for all observed molecules. We derived the rotational constants for the C^13^C^34^S, CC^33^S, CCC^33^S, HC^33^S+, and HCC^34S^+ isotopologues from new laboratory data and complemented them with the frequencies of the observed lines. We find that all sulphur isotopologues are consistent with solar isotopic abundance ratios. Accurate ^12^C/^13^C abundances were derived and, as previously suggested, the ^13^C isotopologues of CCS and CCCS show strong abundance anomalies depending on the position of the substituted carbon. Nevertheless, the ^12^C/^13^C abundance ratio is practically identical to the solar value for CS, HCS+, and H_2_CS. We also searched for the isotopologues of other S-bearing molecules in the 31-50 GHz domain (HCS, HSC, NCS, H_2_CCS, HCSCN, HCCCS+, C_4_S, and C5S). The expected intensities for their ^34^S and ^13^C isotopologues are too low to be detected with the present sensitivity of the QUIJOTE line survey, however. The results presented in this work provide new insights into the molecular composition, isotopic abundances, and physical conditions of the cold starless core TMC-12025A&A...702A..23Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/702/A23CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/702/A23https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/702/A23http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/702/A23https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/702/A23https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/702/A23http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/702/A23GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/A+A/702/A23/tableb1Observed line parameters for S-bearing species and their isotopologues in this studyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMolMoleculemeta.notecharn_Mol[*#] Note on Mol (1)meta.notecharTransTransitionmeta.id;phys.atmol.transitioncharFu-FlTransition (Fu-Fl)meta.id;phys.atmol.transitioncharnurestAdopted rest frequency (see text)MHzem.freqdoublee_nurestAdopted rest frequency error (1sigma)MHzstat.errorfloatvLSR? Local standard of rest (LSR) velocity of the line (2)km/sphys.veloc;pos.lsrfloatnullablee_vLSR? Local standard of rest (LSR) velocity of the line error (1sigma)km/sstat.error;phys.veloc;pos.lsrfloatnullableInt(T*Adv)? Integrated line intensitymK.km**-1.sspect.line.intensityfloatnullablee_Int(T*Adv)? Integrated line intensity error (1sigma)mK.km**-1.sstat.errorfloatnullableDeltav? Linewidth at half intensity derived by fitting a Gaussian function to the observed line profilekm/sspect.line.widthfloatnullablee_Deltav? Linewidth at half intensity derived by fitting a Gaussian function to the observed line profile error (1sigma)km/sstat.errorfloatnullablel_T*A[<= ] Limit flag on T*A (3sigma)meta.code.errorcharT*A? Antenna temperaturemKphot.antennaTempfloatnullablee_T*A? Antenna temperature error (1sigma)mKstat.errorfloatnullablen_T*A[fg] Note on T*A (3)meta.notechar