J/A+A/620/A80ivo://CDS.VizieR/J/A+A/620/A80doi:10.26093/cds/vizier.36200080CDSMarcelino N.Gerin M.Cernicharo J.Fuente A.Wootten H.A.,Chapillon E.Pety J.Lis D.C.Roueff E.Commercon B.Ciardi A.2018-11-30T12:27:01Z2018-11-30T08:10:08ZCDS support team

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

cds-question@unistra.frmolecular-cloudsspectroscopyThe Barnard 1b core shows signatures of being at the earliest stages of low- mass star formation, with two extremely young and deeply embedded proto- stellar objects. Hence, this core is an ideal target to study the structure and chemistry of the first objects formed in the collapse of prestellar cores. We present ALMA Band 6 spectral line observations at ~0.6" of angular resolution towards Barnard 1b. We have extracted the spectra towards both protostars, and used a local thermodynamic equilibrium (LTE) model to reproduce the observed line profiles. B1b-S shows rich and complex spectra, with emission from high energy transitions of complex molecules, such as CH_3_OCOH and CH_3_CHO, including vibrational level transitions. We have tentatively detected for the first time in this source emission from NH_2_CN, NH_2_CHO, CH_3_CH_2_OH, CH_2_OHCHO, CH_3_CH_2_OCOH and both aGg' and gGg' conformers of (CH_2_OH)_2_. This is the first detection of ethyl formate (CH_3_CH_2_OCOH) towards a low-mass star forming region. On the other hand, the spectra of the FHSC candidate B1b-N are free of COMs emission. In order to fit the observed line profiles in B1b-S, we used a source model with two components: an inner hot and compact component (200K, 0.35") and an outer and colder one (60K, 0.6"). The resulting COM abundances in B1b-S range from 10^-13^ for NH_2_CN and NH_2_CHO, up to 10^-9^ for CH_3_OCOH. Our ALMA Band 6 observations reveal the presence of a compact and hot component in B1b-S, with moderate abundances of complex organics. These results indicate that a hot corino is being formed in this very young Class 0 source.2018A&A...620A..80Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/620/A80CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/620/A80https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/620/A80http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/620/A80https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/620/A80https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/620/A80http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/620/A80GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/620/A80/tableb2*Observed transitions in B1b-SrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsFreq? Observed frequencyMHzem.freqdoublenullableMolMolecule formulameta.notecharTransQuantum numbers of the transitionphys.atmol.qn;phys.atmol.transitionRestFreq? Rest frequency from the cataloguesMHzem.freqdoublenullablee_RestFreq? Uncertainty for the rest frequencyMHzstat.errorfloatnullableEup? Upper state energyKphys.energy;phys.atmol.levelfloatnullableSij? Line strengthspect.line.intensityfloatnullableAij? Einstein coefficients**-1phys.atmol.transProbdoublenullableIntArea? Integrated area of the lineK.km/sphys.area;spect.linefloatnullablee_IntArea? Uncertainty for the integrated areaK.km/sstat.errorfloatnullablevLSR? LSR velocitykm/sphys.veloc;pos.lsrfloatnullablee_vLSR? Uncertainty for the LSR velocitykm/sstat.error;phys.veloc;pos.lsrfloatnullableDeltav? Line widthkm/sspect.line.widthfloatnullablee_Deltav? Uncertainty for the line widthkm/sstat.errorfloatnullableTB? Brightness temperatureKphys.temperaturefloatnullablerms? rms of the spectra near the lineKstat.stdev;instr.det.noise;spect.linefloatnullableNotesNote (1)meta.notechar