J/A+A/646/A72ivo://CDS.VizieR/J/A+A/646/A72doi:10.26093/cds/vizier.36460072CDSHarsono D.van der Wiel M.H.D.Bjerkeli P.Ramsey J.P.Calcutt H.,Kristensen L.E.Joergensen J.K.2021-07-05T07:36:38Z2021-02-12T10:38:05ZCDS support team

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

cds-question@unistra.frprotostarschemical-abundancesradio-spectroscopyPhysical processes that govern the star and planet formation sequence influence the chemical composition and evolution of protoplanetary disks. Recent studies allude to an early start to planet formation already ongoing during the formation of a disk. To understand the chemical composition of protoplanets, we need to constrain the composition and structure of the disks from whence they are formed. We aim to determine the molecular abundance structure of the young disk around the TMC1A protostar on au scales in order to understand its chemical structure and any possible implications for disk formation. We present spatially resolved Atacama Large Millimeter/submillimeter Array observations of CO, HCO^+^, HCN, DCN, and SO line emission, as well as dust continuum emission, in the vicinity of TMC1A. Molecular column densities are estimated both under the assumption of optically thin emission from molecules in local thermodynamical equilibrium (LTE) as well as through more detailed non-LTE radiative transfer calculations. From the derived HCO^+^ abundance, we estimate the ionization fraction of the disk surface and find values that imply that the accretion process is not driven by the magneto-rotational instability. The molecular abundances averaged over the TMC1A disk are similar to its protostellar envelope and other, older Class II disks. We meanwhile find a discrepancy between the young disk's molecular abundances relative to Solar System objects. Abundance comparisons between the disk and its surrounding envelope for several molecular species reveal that the bulk of planet-forming material enters the disk unaltered. Differences in HCN and H_2_O molecular abundances between the disk around TMC1A, Class II disks, and Solar System objects trace the chemical evolution during disk and planet formation.2021A&A...646A..72Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/646/A72CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/646/A72https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/646/A72http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/646/A72https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/646/A72https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/646/A72http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/646/A72GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/646/A72/list (List of fits datacubes and images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/646/A72/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/646/A72/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/646/A72/list?GETtext/xml+votable180.050000true69.8966725.695620.0055555555555555566/1054https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/646/A72?format=asciiMillimeterdefaultJ/A+A/646/A72/table2Properties of the ALMA images including noise and integrated flux densityrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of the datameta.id;meta.mainFreqFrequency of the dataGHzem.freqdoubleEup? Upper enery level (1)Kphys.energy;phys.atmol.levelfloatnullableLogAij? Logarithmic of the Einstein Alog(s**-1)phys.atmol.transProbfloatnullableBeam1Beam information, FWHM of the major axisarcsecmeta.note;phys.angSize;instr.beamfloatBeam2Beam information, FWHM of the minor axisarcsecmeta.note;phys.angSize;instr.beamfloatPA[] Beam information, position angledegmeta.note;pos.posAng;instr.beamfloatNoiseNoise levelmJy/beaminstr.det.noisefloatTimeThe final integrated time based on the visibilitiesstime.epochintl_IntLimit flag on Intmeta.code.errorcharIntIntegrated flux inside 1" (2)mJy.km/sphot.flux.densityinte_Int? Error on integrated flux inside 1" (2)mJy.km/sstat.errorintnullableJ/A+A/646/A72/listList of fits datacubes and imagesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintNz? Number of slices for the datacubesmeta.numberintnullableObs.dateObservation datestime.epoch;obsnullablebVRAD? Lower value of VRAD interval for datacubesm/sphys.veloc;pos.heliocentricdoublenullableBVRAD? Upper value of VRAD interval for datacubesm/sphys.veloc;pos.heliocentricfloatnullabledVRAD? VRAD resolution for datacubesm/sspect.resolutionfloatnullableFreqObserved frequencyGHzem.freqfloatsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fits