J/ApJ/908/8ivo://CDS.VizieR/J/ApJ/908/8doi:10.26093/cds/vizier/ba-wc-8CDSCalahan J.K.Bergin E.Zhang KeTeague R.Cleeves I.Bergner J.,Blake G.A.Cazzoletti P.Guzman V.Hogerheijde M. RHuang J.Kama M.,Loomis R.Oberg K.Qi C.van Dishoeck E.F.van Scheltinga J.T.,Walsh C.Wilner D.2026-07-02T11:58:12Z2025-04-11T10:16:47ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsco-line-emissionmolecular-physicsmillimeter-astronomysubmillimeter-astronomyinterstellar-mediumThe thermal structure of protoplanetary disks is a fundamental characteristic of the system that has wide-reaching effects on disk evolution and planet formation. In this study, we constrain the 2D thermal structure of the protoplanetary disk TW Hya structure utilizing images of seven CO lines. This includes new ALMA observations of ^12^CO J=2-1 and C^18^O J=2-1 as well as archival ALMA observations of ^12^CO J=3-2, ^13^CO J=3-2 and 6-5, and C^18^O J=3-2 and 6-5. Additionally, we reproduce a Herschel observation of the HD J=1-0 line flux and the spectral energy distribution and utilize a recent quantification of CO radial depletion in TW Hya. These observations were modeled using the thermochemical code RAC2D, and our best-fit model reproduces all spatially resolved CO surface brightness profiles. The resulting thermal profile finds a disk mass of 0.025M_{sun}_ and a thin upper layer of gas depleted of small dust with a thickness of ~1.2% of the corresponding radius. Using our final thermal structure, we find that CO alone is not a viable mass tracer, as its abundance is degenerate with the total H2 surface density. Different mass models can readily match the spatially resolved CO line profiles with disparate abundance assumptions. Mass determination requires additional knowledge, and, in this work, HD provides the additional constraint to derive the gas mass and support the inference of CO depletion in the TW Hya disk. Our final thermal structure confirms the use of HD as a powerful probe of protoplanetary disk mass. Additionally, the method laid out in this paper is an employable strategy for extraction of disk temperatures and masses in the future.2021ApJ...908....8Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/908/8CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)I/345 : Gaia DR2 (Gaia Collaboration, 2018)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)J/ApJ/828/46 : ALMA survey of Lupus protoplanetary disks. I. (Ansdell+, 2016)J/A+A/592/A49 : TW Hya CO (2-1), CN (2-1) & CS (5-4) data (Teague+, 2016)J/A+A/592/A83 : HD 100546 and TW Hya model abundances (Kama+, 2016)J/A+A/594/A85 : 2D disk models from CO isotopologues line (Miotello+, 2016)J/ApJ/862/L2 : Detection of HCOOH in TW Hya disk with ALMA (Favre+, 2018)J/A+A/642/L15 : Near-infrared spectra for TW Hya (McLure+, 2020)J/A+A/648/A33 : ALMA continuum images of TW Hya (Macias+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/908/8https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/908/8http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/908/8https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/908/8https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/908/8http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/908/8GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapMillimeterRadiodefaultJ/ApJ/908/8/fig6The final 2D thermal structure of the gas that reproduces seven resolved ALMA CO lines, HD flux, and the SED (Data behind Figure 6)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRad[0.1/200] RadiusAUphys.size.radiusdoubleH[0/100] HeightAUphys.sizedoubleTg[10/71210]? Gas temperatureKphys.temperaturedoublenullableTd[10.6/188.7]? Dust temperatureKphys.temperaturedoublenullablenGas[10.2/3.41e+12]? Gas number density; particles/H atoms per cm^3^cm**-3meta.id;meta.maindoublenullable