J/A+A/592/A83ivo://CDS.VizieR/J/A+A/592/A83doi:10.26093/cds/vizier.35920083CDSKama M.Bruderer S.Dishoeck E.F.vanHogerheijde M.Folsom C.P.,Miotello A.Fedele D.Belloche A.Gusten R.Wyrowski F.2016-08-02T08:50:13Z2016-08-02T09:44:18ZCDS support team

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

cds-question@unistra.fryoung-stellar-objectsastronomical-modelschemical-abundancesThe composition of planetary solids and gases is largely rooted in the processing of volatile elements in protoplanetary disks. To shed light on the key processes, we carry out a comparative analysis of the gas-phase carbon abundance in two systems with a similar age and disk mass, but different central stars: HD 100546 and TW Hya. We combine our recent detections of C0 in these disks with observations of other carbon reservoirs (CO, C^+^, C_2_H) and gas-mass and warm-gas tracers (HD, O^0^), as well as spatially resolved ALMA observations and the spectral energy distribution. The disks are modelled with the DALI 2D physical-chemical code. Stellar abundances for HD 100546 are derived from archival spectra. Upper limits on HD emission from HD 100546 place an upper limit on the total disk mass of <=0.1M_{sun}_. The gas-phase carbon abundance in the atmosphere of this warm Herbig disk is, at most, moderately depleted compared to the interstellar medium, with Bootis star, with solar abundances of C and O but a strong depletion of rockforming elements. In the gas of the T Tauri disk TW Hya, both C and O are strongly underabundant, with [C]/[H]_gas_=(0.2-5.0)x10^-6^ and C/O>1. We discuss evidence that the gas-phase C and O abundances are high in the warm inner regions of both disks. Our analytical model, including vertical mixing and a grain size distribution, reproduces the observed [C]/[H]_gas_ in the outer disk of TW Hya and allows to make predictions for other systems.2016A&A...592A..83Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/592/A83CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/592/A83https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/592/A83http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/592/A83https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/592/A83https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/592/A83http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/592/A83GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/592/A83/hd_gd10HD 100546 model, solution with low gas-to-dust ratio (10) and solar carbon (C/H=1e-4)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintrmidRadial central point of the grid cell (star=0) (r_mid(au))AUstat.fit.paramdoublezmidVertical central point of the grid cell (midplane=0) (z_mid(au))AUstat.fit.paramdoublengasTotal number density of gas in the cell (n_gas(cm-3))cm**-2phys.densitydoubletgasGas temperature(t_gas(K))Kphys.temperaturedoubletdustDust temperature(t_dust(K))Kphys.temperaturedoubleG0unattUnattenuated local UV field in Draine units (2.7e-3erg/s/cm2 between 911{AA} and 2067{AA}) (G_0_unatt)phot.flux;em.UVdoubleG0Local UV field in Draine units (2.7e-3erg/s/cm2 between 911{AA} and 2067{AA}) (G_0)phot.flux;em.UVcharAVEffective A_V_ (A_UV=-log10(G0/G0_unatt), A_V=A_UV/3) (A_V)magphys.absorptiondoubleHNumber density of atomic hydrogen (H)phys.densitydoubleH2Number density of molecular hydrogen (H2)phys.densitydoublee-Number density of free electrons (e-)phys.densitydoubleCNumber density of atomic carbon (C)phys.densitydoubleCONumber density of carbon monoxide (CO)phys.densitydoubleONumber density of atomic oxygen (O)phys.densitydoubleJ/A+A/592/A83/hd_gd100HD 100546 model, solution with standard gas-to-dust (100) and somewhat depleted carbon (C/H=1e-5)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintrmidRadial central point of the grid cell (star=0) (r_mid(au))AUstat.fit.paramdoublezmidVertical central point of the grid cell (midplane=0) (z_mid(au))AUstat.fit.paramdoublengasTotal number density of gas in the cell (n_gas(cm-3))cm**-2phys.densitydoubletgasGas temperature(t_gas(K))Kphys.temperaturedoubletdustDust temperature(t_dust(K))Kphys.temperaturedoubleG0unattUnattenuated local UV field in Draine units (2.7e-3erg/s/cm2 between 911{AA} and 2067{AA}) (G_0_unatt)phot.flux;em.UVdoubleG0Local UV field in Draine units (2.7e-3erg/s/cm2 between 911{AA} and 2067{AA}) (G_0)phot.flux;em.UVcharAVEffective A_V_ (A_UV=-log10(G0/G0_unatt), A_V=A_UV/3) (A_V)magphys.absorptiondoubleHNumber density of atomic hydrogen (H)phys.densitydoubleH2Number density of molecular hydrogen (H2)phys.densitydoublee-Number density of free electrons (e-)phys.densitydoubleCNumber density of atomic carbon (C)phys.densitydoubleCONumber density of carbon monoxide (CO)phys.densitydoubleONumber density of atomic oxygen (O)phys.densitydoubleJ/A+A/592/A83/tw_co1_5TW Hya model, C/H=1e-6, O/H=6.67e-7recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintrmidRadial central point of the grid cell (star=0) (r_mid(au))AUstat.fit.paramdoublezmidVertical central point of the grid cell (midplane=0) (z_mid(au))AUstat.fit.paramdoublengasTotal number density of gas in the cell (n_gas(cm-3))cm**-2phys.densitydoubletgasGas temperature(t_gas(K))Kphys.temperaturedoubletdustDust temperature(t_dust(K))Kphys.temperaturedoubleG0unattUnattenuated local UV field in Draine units (2.7e-3erg/s/cm2 between 911{AA} and 2067{AA}) (G_0_unatt)phot.flux;em.UVdoubleG0Local UV field in Draine units (2.7e-3erg/s/cm2 between 911{AA} and 2067{AA}) (G_0)phot.flux;em.UVcharAVEffective A_V_ (A_UV=-log10(G0/G0_unatt), A_V=A_UV/3) (A_V)magphys.absorptiondoubleHNumber density of atomic hydrogen (H)phys.densitydoubleH2Number density of molecular hydrogen (H2)phys.densitydoublee-Number density of free electrons (e-)phys.densitydoubleCNumber density of atomic carbon (C)phys.densitydoubleCONumber density of carbon monoxide (CO)phys.densitydoubleONumber density of atomic oxygen (O)phys.densitydouble