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-disc interactions and disc 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 ($0.15^{\prime \prime }-0.30^{\prime \prime }$), 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 discs 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 disc: 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 disc eccentricities or warps, potentially induced by a substellar companion in the inner regions of the system.

Accepted for publication in ApJL as part of the exoALMA series

References in corpus (41)

• Array Programming with NumPy
• scikit-image: Image processing in Python
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• PLUTO: a Numerical Code for Computational Astrophysics
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations
• CMasher: Scientific colormaps for making accessible, informative and 'cmashing' plots
• Asymmetric features in the protoplanetary disk MWC758
• Meridional flows in the disk around a young star
• The efficiency of dust trapping in ringed proto-planetary discs
• Gas and dust dynamics in starlight-heated protoplanetary disks
• A new planet candidate detected in a dust gap of the disc around HD 163296 through localised kinematic signatures. An observational validation of the Discminer
• Vortices and spirals in the HD135344B transition disk
• Dust traps in the protoplanetary disc MWC 758: two vortices produced by two giant planets?
• The Disc Miner I: A statistical framework to detect and quantify kinematical perturbations driven by young planets in discs
• Molecules with ALMA at Planet-forming Scales (MAPS). A Circumplanetary Disk Candidate in Molecular Line Emission in the AS 209 Disk
• Hydro-, Magnetohydro-, and Dust-Gas Dynamics of Protoplanetary Disks
• A dusty filament and turbulent CO spirals in HD135344B-SAO206462
• Setting the Stage for Planet Formation: Measurements and Implications of the Fundamental Disk Properties
• Gravitational instability in a planet-forming disk
• The Disc Miner II: Revealing Gas substructures and Kinematic signatures from Planet-disc interaction through line profile analysis
• Observational Signatures of Tightly Wound Spirals Driven by Buoyancy Resonances in Protoplanetary Disks
• Kinematics and brightness temperatures of transition discs -- A survey of gas substructures as seen with ALMA
• Are the spiral arms in the MWC 758 protoplanetary disc driven by a companion inside the cavity?
• Dynamical Evidence of a Spiral Arm--Driving Planet in the MWC 758 Protoplanetary Disk
• Protoplanetary disks in $K_s$-band total intensity and polarized light
• SO and SiS Emission Tracing an Embedded Planet and Compact ${}^{12}$CO and ${}^{13}$CO Counterparts in the HD 169142 Disk
• exoALMA V: Gaseous Emission Surfaces and Temperature Structures
• exoALMA III: Line-intensity Modeling and System Property Extraction from Protoplanetary Disks
• A kinematically detected planet candidate in a transition disk
• exoALMA XII: Weighing and sizing exoALMA disks with rotation curve modelling
• exoALMA IV: Substructures, Asymmetries, and the Faint Outer Disk in Continuum Emission
• Constraining Protoplanetary Disk Accretion and Young Planets Using ALMA Kinematic Observations
• Mapping the Planetary Wake in HD 163296 with Kinematics
• PPDONet: Deep Operator Networks for Fast Prediction of Steady-State Solutions in Disk-Planet Systems
• exoALMA. VI. Rotating under Pressure: Rotation curves, azimuthal velocity substructures, and pressure variations
• Probing the eccentricity in protostellar discs -- Modeling kinematics and morphologies
• exoALMA. XVII. Characterizing the Gas Dynamics around Dust Asymmetries
• Circumplanetary Disk Candidate in the Disk of HD 163296 Traced by Localized Emission from Simple Organics
• exoALMA XXI: The Morphology and Dynamics of Vertical Flows

Cited by in corpus (1)

• exoALMA XXI: The Morphology and Dynamics of Vertical Flows