exoALMA. XX. Tomographic Detection of Embedded Planets in Protoplanetary Disks

Abstract The exoALMA Large Program has revealed a wealth of substructures in the dust and molecular line emission of several protoplanetary discs, suggesting that planet formation may unfold within highly dynamic environments. Using synthetic observations of planet–disk interactions and disk instabilities, we demonstrate how the origin of these substructures can be investigated through a tomographic study of molecular lines, extending the scope of the analysis beyond line-centroid kinematics alone. Our results indicate that with only a few hours of ALMA integration at moderate angular 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:mo>−</mml:mo> <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>30</mml:mn> </mml:math> ), it is possible to identify the key signatures driven by planets more massive than 0.1% of the stellar mass. These signatures manifest not only as deviations from Keplerian motion but also as localized line broadening, enabling accurate constraints on the orbital radius and azimuthal location of the planets. We further show that a diagnostic based on line skewness in spectrally resolved observations can help distinguish between planetary and instability-driven signatures, owing to the distinct degrees of velocity coherence associated with each mechanism. Finally, we apply this tomographic analysis to exoALMA CO line data for the disks of HD 135344B and MWC 758. In HD 135344B, we identify strongly localized velocity and line-width perturbations, suggesting the possibility of three massive planets embedded in the disk: one at R = 95 au, exterior to the continuum substructures, and two within dust gaps at R = 41 au and R = 73 au. For MWC 758, the dominance of vertical-velocity spirals over localized signatures is consistent with predictions from models of moderate disk eccentricities or warps, potentially induced by a substellar companion in the inner regions of the system.

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Publication Details

Journal
The Astrophysical Journal Letters
Published
2026-03-16
DOI
https://doi.org/10.3847/2041-8213/ae48fd
Citations
1
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
23.83
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article

exoALMA. XX. Tomographic Detection of Embedded Planets in Protoplanetary Disks

Maria Galloway-Sprietsma, Brianna Zawadzki, D. J. Price, Lisa Wölfer et al.
1 citations
The Astrophysical Journal Letters
Astrophysics and Star Formation Studies
23.83
article

exoALMA. XX. Tomographic Detection of Embedded Planets in Protoplanetary Disks

Maria Galloway-Sprietsma, Brianna Zawadzki, D. J. Price, Lisa Wölfer, J. Bae, Andrew J. Winter, Misato Fukagawa, Gianni Cataldi, Sean M. Andrews, Richard Teague, Cassandra Hall, Ryan A. Loomis, Jane Huang, John D. Ilee, C. Pinte, Marcelo Barraza-Alfaro, Jensen Lawrence, Cristiano Longarini, Andrés F. Izquierdo, Pietro Curone, Daniele Fasano, Geoffroy Lesur, Ian Czekala, Jochen Stadler, G. Lodato, Leonardo Testi, Mario Flock, Nicolás Cuello, Andrea Isella, Stefano Facchini, David J. Wilner, Giovanni Rosotti, Myriam Benisty, Ewine F. van Dishoeck, François Ménard
article en
1 citations

Abstract

Abstract The exoALMA Large Program has revealed a wealth of substructures in the dust and molecular line emission of several protoplanetary discs, suggesting that planet formation may unfold within highly dynamic environments. Using synthetic observations of planet–disk interactions and disk instabilities, we demonstrate how the origin of these substructures can be investigated through a tomographic study of molecular lines, extending the scope of the analysis beyond line-centroid kinematics alone. Our results indicate that with only a few hours of ALMA integration at moderate angular 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:mo>−</mml:mo> <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>30</mml:mn> </mml:math> ), it is possible to identify the key signatures driven by planets more massive than 0.1% of the stellar mass. These signatures manifest not only as deviations from Keplerian motion but also as localized line broadening, enabling accurate constraints on the orbital radius and azimuthal location of the planets. We further show that a diagnostic based on line skewness in spectrally resolved observations can help distinguish between planetary and instability-driven signatures, owing to the distinct degrees of velocity coherence associated with each mechanism. Finally, we apply this tomographic analysis to exoALMA CO line data for the disks of HD 135344B and MWC 758. In HD 135344B, we identify strongly localized velocity and line-width perturbations, suggesting the possibility of three massive planets embedded in the disk: one at R = 95 au, exterior to the continuum substructures, and two within dust gaps at R = 41 au and R = 73 au. For MWC 758, the dominance of vertical-velocity spirals over localized signatures is consistent with predictions from models of moderate disk eccentricities or warps, potentially induced by a substellar companion in the inner regions of the system.

The Astrophysical Journal LettersVol. 1000(1)
Wesleyan University (US), Leiden University (NL), Centre National de la Recherche Scientifique (FR), University of Leeds (GB), European Southern Observatory (DE), University of Georgia (US), Queen Mary University of London (GB), University of St Andrews (GB), University of Milan (IT), Université Côte d'Azur (FR), University of Cambridge (GB), National Radio Astronomy Observatory (US), University of Florida (US), Osservatorio astronomico di Bologna (IT), Max Planck Institute for Extraterrestrial Physics (DE), Max Planck Institute for Astronomy (DE), Center for Astrophysics Harvard & Smithsonian (US), Observatoire de la Côte d’Azur (FR), Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (IT), National Astronomical Observatory of Japan (JP), Monash University (AU), Massachusetts Institute of Technology (US), University of Chile (CL), Rice University (US), Columbia University (US), Université Grenoble Alpes (FR), University of Bologna (IT)
Openalex Percentile: Top 1%
Astrophysics and Star Formation Studies
23.83
DOIOpen Access PDFOpenAlex
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