exoALMA. XIX. Confirmation of Non-thermal Line Broadening in the DM Tau Protoplanetary Disk

Abstract Turbulence is expected to transport angular momentum and drive mass accretion in protoplanetary disks. One way to directly measure turbulent motion in disks is through molecular line broadening. DM Tau is one of only a few disks with claimed detection of nonthermal line broadening of 0.25 c s –0.33 c s , where c s is the sound speed. Using the radiative transfer code mcfost within a Bayesian inference framework that evaluates over five million disk models to efficiently sample the parameter space, we fit high-resolution ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>.</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>″</mml:mi> </mml:mrow> </mml:mover> <mml:mn>15</mml:mn> </mml:math> , 28 m s −1 ) 12 CO J = 3–2 observations of DM Tau from the exoALMA Large Program. This approach enables us to simultaneously constrain the disk structure and kinematics, revealing a significant nonthermal contribution to the line width of ∼0.4 c s , inconsistent with purely thermal motions. Using the CO-based disk structure as a starting point, we reproduce the CS J = 7–6 emission well, demonstrating that the CS (which is more sensitive to nonthermal motions than CO) agrees with the turbulence inferred from the CO fit. Establishing a well-constrained background disk model further allows us to identify residual structures in the moment maps that deviate from the expected emission, revealing localized perturbations that may trace forming planets. This framework provides a powerful general approach for extracting disk structure and nonthermal broadening directly from molecular line data and can be applied to other disks with high-quality observations.

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Publication Details

Journal
The Astrophysical Journal Letters
Published
2026-01-30
DOI
https://doi.org/10.3847/2041-8213/ae313a
Citations
2
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
47.65

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article

exoALMA. XIX. Confirmation of Non-thermal Line Broadening in the DM Tau Protoplanetary Disk

Maria Galloway-Sprietsma, Brianna Zawadzki, D. J. Price, Lisa Wölfer et al.
2 citations
The Astrophysical Journal Letters
Astrophysics and Star Formation Studies
47.65
article

exoALMA. XIX. Confirmation of Non-thermal Line Broadening in the DM Tau Protoplanetary Disk

Maria Galloway-Sprietsma, Brianna Zawadzki, D. J. Price, Lisa Wölfer, Misato Fukagawa, Thomas Hilder, Gianni Cataldi, Richard Teague, Ryuta Orihara, Ryan A. Loomis, Iain Hammond, John D. Ilee, C. Pinte, Marcelo Barraza-Alfaro, Cristiano Longarini, Andrés F. Izquierdo, Daniele Fasano, Geoffroy Lesur, Caitlyn Hardiman, J.H. Bae, Tomohiro C. Yoshida, Mario Flock, Giovanni P. Rosotti, Ian Czekala, Taïssa Danilovich, Myriam Benisty, Hsi-Wei Yen, Kazuhiro Kanagawa, Jochen Stadler, Sean M. Andrews, Andrew J. Winter, Pietro Curone, Nicolás Cuello, David J. Wilner, Stefano Facchini, Gaylor Wafflard- Fernandez, Himanshi Garg, Jane Huang, Giuseppe Lodato, Francois Menard
article en
2 citations

Abstract

Abstract Turbulence is expected to transport angular momentum and drive mass accretion in protoplanetary disks. One way to directly measure turbulent motion in disks is through molecular line broadening. DM Tau is one of only a few disks with claimed detection of nonthermal line broadening of 0.25 c s –0.33 c s , where c s is the sound speed. Using the radiative transfer code mcfost within a Bayesian inference framework that evaluates over five million disk models to efficiently sample the parameter space, we fit high-resolution ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>.</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>″</mml:mi> </mml:mrow> </mml:mover> <mml:mn>15</mml:mn> </mml:math> , 28 m s −1 ) 12 CO J = 3–2 observations of DM Tau from the exoALMA Large Program. This approach enables us to simultaneously constrain the disk structure and kinematics, revealing a significant nonthermal contribution to the line width of ∼0.4 c s , inconsistent with purely thermal motions. Using the CO-based disk structure as a starting point, we reproduce the CS J = 7–6 emission well, demonstrating that the CS (which is more sensitive to nonthermal motions than CO) agrees with the turbulence inferred from the CO fit. Establishing a well-constrained background disk model further allows us to identify residual structures in the moment maps that deviate from the expected emission, revealing localized perturbations that may trace forming planets. This framework provides a powerful general approach for extracting disk structure and nonthermal broadening directly from molecular line data and can be applied to other disks with high-quality observations.

The Astrophysical Journal LettersVol. 997(2)
National Science Foundation, National Aeronautics and Space Administration, National Geographic Society, Space Telescope Science Institute, National Radio Astronomy Observatory, Australian Government, University of Leeds, European Commission, Fondazione Cariplo, Nuclear Safety and Security Commission, Agencia Nacional de Investigación y Desarrollo, HORIZON EUROPE Framework Programme, Science and Technology Facilities Council, Japan Society for the Promotion of Science
Openalex Percentile: Top 0%
Astrophysics and Star Formation Studies
47.65
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