2020/12/10 by Jenny K. Calahan, Jenny Calahan, Edwin Bergin +19 · 58 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Brightness #Flux (metallurgy) #Line (geometry) #Planet #Planetary system #Protoplanet #Protoplanetary disk #Stellar, planetary, and galactic studies #Surface brightness #Thermal #astro-ph.EP
paper · pdf · doi:10.3847/1538-4357/abd255
published in The Astrophysical Journal 908(1), 8 (IOP Publishing) · 28 pages, 12 main figures, 14 appendix figures. Accepted to ApJ
arxiv created 2020/12/10 · openalex created_date 2020/12/21 · openalex publication_date 2021/02/01 · arxiv updated 2021/02/17 · openalex updated_date 2026/08/06
Abstract 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 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 0.025 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 H 2 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.