J/ApJ/908/8 The TW Hya Rosetta Stone Project. III. (Calahan+, 2021)
The TW Hya Rosetta Stone Project.
III. Resolving the gaseous thermal profile of the disk.
Calahan J.K., Bergin E., Zhang Ke, Teague R., Cleeves I., Bergner J.,
Blake G.A., Cazzoletti P., Guzman V., Hogerheijde M. R, Huang J., Kama M.,
Loomis R., Oberg K., Qi C., van Dishoeck E.F., van Scheltinga J.T.,
Walsh C., Wilner D.
<Astrophys. J., 908, 8 (2021)>
=2021ApJ...908....8C 2021ApJ...908....8C
ADC_Keywords: Stars, pre-main sequence; Carbon monoxide; Molecular data;
Millimetric/submm sources; Interstellar medium
Keywords: Protoplanetary disks ; Astrochemistry
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 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
0.025M☉ 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.
Description:
We present new Atacama Large Millimeter/submillimeter Array (ALMA)
observations of 12CO 2-1 and C18O 2-1 taken as a part of the
Rosetta collaboration; program 2016.1.00311.S (PI Cleeves). The
compact observations (baselines down to 15m) were obtained on
2016 December 16 in configuration C43-3 for a total on-source
integration time of 81 minutes. The extended observations (baselines
up to 1124m) were carried out on 2017 May 5 and 7 in C43-6 with an
on-source integration time of 25 minutes. See Section 2.1.
Archival ALMA data were also used for 12CO 3-2, C18O 3-2 and 6-5,
and 13CO 3-2 and 6-5. Observations are described in
Schwarz+ (2016ApJ...823...91S 2016ApJ...823...91S).
The archival HD J=1-0 flux measurement from Herschel and SED fluxes
from the literature were also used. Data points for the SED were taken
from Cleeves+ (2015ApJ...799..204C 2015ApJ...799..204C). See Section 2.3.
Integrated emission maps of TW Hya in 12CO J=2-1 and 3-2,
13CO J=3-2 and 6-5, and C18O J=2-1, 3-2, and 6-5 are presented in
Figure 1.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
11 01 51.90 -34 42 17.0 TW Hya = V* TW Hya
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig6.dat 49 10000 The final 2D thermal structure of the gas that
reproduces seven resolved ALMA CO lines, HD flux,
and the SED (Data behind Figure 6)
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See also:
I/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)
Byte-by-byte Description of file: fig6.dat
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Bytes Format Units Label Explanations
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1- 9 E9.3 AU Rad [0.1/200] Radius
11- 19 E9.3 AU H [0/100] Height
21- 29 E9.3 K Tg [10/71210]? Gas temperature
31- 39 E9.3 K Td [10.6/188.7]? Dust temperature
41- 49 E9.3 cm-3 nGas [10.2/3.41e+12]? Gas number density;
particles/H atoms per cm3
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS] 23-Jun-2022