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The TW Hya Rosetta Stone Project. III. Resolving the Gaseous Thermal Profile of the Disk

Calahan, Jenny K. and Bergin, Edwin and Zhang, Ke and Teague, Richard and Cleeves, Ilsedore and Bergner, Jennifer and Blake, Geoffrey A. and Cazzoletti, Paolo and Guzmán, Viviana and Hogerheijde, Michiel R. and Huang, Jane and Kama, Mihkel and Loomis, Ryan and Öberg, Karin and Qi, Charlie and van Dishoeck, Ewine F. and Terwisscha van Scheltinga, Jeroen and Walsh, Catherine and Wilner, David (2021) The TW Hya Rosetta Stone Project. III. Resolving the Gaseous Thermal Profile of the Disk. Astrophysical Journal, 908 (1). Art. No. 8. ISSN 1538-4357. doi:10.3847/1538-4357/abd255.

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The 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 ¹²CO J = 2–1 and C¹⁸O J = 2–1 as well as archival ALMA observations of ¹²CO J = 3–2, ¹³CO J = 3–2 and 6–5, and C¹⁸O 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 0.025 M_⊙ 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Calahan, Jenny K.0000-0002-0150-0125
Bergin, Edwin0000-0003-4179-6394
Zhang, Ke0000-0002-0661-7517
Teague, Richard0000-0003-1534-5186
Cleeves, Ilsedore0000-0003-2076-8001
Bergner, Jennifer0000-0002-8716-0482
Blake, Geoffrey A.0000-0003-0787-1610
Cazzoletti, Paolo0000-0002-1917-7370
Guzmán, Viviana0000-0003-4784-3040
Hogerheijde, Michiel R.0000-0001-5217-537X
Huang, Jane0000-0001-6947-6072
Kama, Mihkel0000-0003-0065-7267
Loomis, Ryan0000-0002-8932-1219
Öberg, Karin0000-0001-8798-1347
Qi, Charlie0000-0001-8642-1786
van Dishoeck, Ewine F.0000-0001-7591-1907
Terwisscha van Scheltinga, Jeroen0000-0002-3800-9639
Walsh, Catherine0000-0001-6078-786X
Wilner, David0000-0003-1526-7587
Additional Information:© 2021. The American Astronomical Society. Received 2020 May 19; revised 2020 December 8; accepted 2020 December 8; published 2021 February 8. This paper makes use of data from ALMA programs 2015.1.00686.S, 2016.1.00629.S, 2012.1.00422.s, and 2016.1.00311.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. J.K.C. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant No. DGE 1256260 and the National Aeronautics and Space Administration FINESST grant, under grant No. 80NSSC19K1534. E.A.B. acknowledges support from NSF grant No. 1907653. K.Z. acknowledges the support of the Office of the Vice Chancellor for Research and Graduate Education at the University of Wisconsin – Madison with funding from the Wisconsin Alumni Research Foundation, and support of the support of NASA through Hubble Fellowship grant HST-HF2-51401.001. awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. L.I.C. gratefully acknowledges support from the David and Lucile Packard Foundation and the Virginia Space Grant Consortium. S. A. and J. H. acknowledge funding support from the National Aeronautics and Space Administration under Grant No. 17-XRP17 2-0012 issued through the Exoplanets Research Program. J. H. acknowledges support for this work provided by NASA through the NASA Hubble Fellowship grant \#HST-HF2-51460.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. C.W. acknowledges financial support from the University of Leeds and the Science and Technology Facilities Council (STFC; grant No. ST/R000549/1). M.K. gratefully acknowledges funding by the University of Tartu ASTRA project 2014-2020.4.01.16-0029 KOMEET "Benefits for Estonian Society from Space Research and Application," financed by the EU European Regional Development Fund. K.Ö. acknowledges support from the Simons Foundation (SCOL 321183) and an NSF AAG Grant (#1907653). Facilities: ALMA - Atacama Large Millimeter Array, Herschel. - Software: RAC2D (Du & Bergin 2014), bettermoments(Teague & Foreman-Mackey 2018), CASA (McMullin et al. 2007).
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1256260
Wisconsin Alumni Research FoundationUNSPECIFIED
University of Wisconsin-MadisonUNSPECIFIED
NASA Hubble FellowshipHST-HF2-51401.001-A
David and Lucile Packard FoundationUNSPECIFIED
Virginia Space Grant ConsortiumUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144152
NASA Hubble FellowshipHST-HF2-51460.001-A
University of LeedsUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/R000549/1
University of Tartu2014-2020.4.01.16-0029
European Union Regional Development FundUNSPECIFIED
Simons FoundationSCOL 321183
Subject Keywords:Protoplanetary disks ; Astrochemistry
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Protoplanetary disks (1300); Astrochemistry (75)
Record Number:CaltechAUTHORS:20210106-102319422
Persistent URL:
Official Citation:Jenny K. Calahan et al 2021 ApJ 908 8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107340
Deposited By: George Porter
Deposited On:07 Jan 2021 15:01
Last Modified:16 Nov 2021 19:01

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