exoALMA. VI. Rotating under Pressure: Rotation curves, azimuthal velocity substructures, and pressure variations

Abstract

The bulk motion of the gas in protoplanetary disks around newborn stars is nearly Keplerian. By leveraging the high angular and spectral resolution of ALMA, we can detect small-scale velocity perturbations in molecular line observations caused by local gas pressure variations in the disk, possibly induced by embedded protoplanets. This paper presents the azimuthally averaged rotational velocity and its deviations from Keplerian rotation ($\delta {\upsilon }_{\varphi }$) for the exoALMA sample, as measured in the ${}^{12}$CO and ${}^{13}$CO emission lines. The rotation signatures show evidence for vertically stratified disks, in which ${}^{13}$CO rotates faster than ${}^{12}$CO due to a distinct thermal gas pressure gradient at their emitting heights. We find $\delta {\upsilon }_{\varphi }$-substructures in the sample on both small ($\sim$10 au) and large ($\sim$100 au) radial scales, reaching deviations up to 15% from background Keplerian velocity in the most extreme cases. More than 75% of the rings and 80% of the gaps in the dust continuum emission resolved in $\delta {\upsilon }_{\varphi }$ are co-located with gas pressure maxima and minima, respectively. Additionally, gas pressure substructures are observed far beyond the dust continuum emission. For the first time, we determined the gas pressure derivative at the midplane from observations and found it to align well with the dust substructures within the given uncertainties. Based on our findings, we conclude that gas pressure variations are likely the dominant mechanism for ring and gap formation in the dust continuum.

arXiv commentThis paper is part of the exoALMA Focus Issue of The Astrophysical Journal Letters. 37 pages, 19 figures

References in corpus (68)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• Gas- and dust evolution in protoplanetary disks
• Accretion Disks Around Young Objects. III. Grain Growth
• Gravitational Instabilities in Circumstellar Disks
• Radial Flow of Dust Particles in Accretion Disks
• The effect of dust settling on the appearance of protoplanetary disks
• Ring shaped dust accumulation in transition disks
• The Disk Substructures at High Angular Resolution Project (DSHARP) VI: Dust trapping in thin-ringed protoplanetary disks
• Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations
• Evidence of fast pebble growth near condensation fronts in the HL Tau protoplanetary disk
• A Kinematical Detection of Two Embedded Jupiter Mass Planets in HD 163296
• Planetary Torques as the Viscosity of Protoplanetary Disks
• On planet formation in HL Tau
• Planets opening dust gaps in gas disks
• A Spatially Resolved Vertical Temperature Gradient in the HD 163296 Disk
• Direct mapping of the temperature and velocity gradients in discs. Imaging the vertical CO snow line around IM Lupi
• Nonlinear propagation of planet-generated tidal waves
• Observations of edge-on protoplanetary disks with ALMA I. Results from continuum data
• Highly structured disk around the planet host PDS 70 revealed by high-angular resolution observations with ALMA
• Formation of a disc gap induced by a planet: Effect of the deviation from Keplerian disc rotation
• Molecules with ALMA at Planet-forming Scales (MAPS) IV: Emission Surfaces and Vertical Distribution of Molecules
• Rossby Wave Instability and three-dimensional vortices in accretion disks
• The efficiency of dust trapping in ringed proto-planetary discs
• Dust distribution in protoplanetary disks - Vertical settling and radial migration
• Homogeneous study of Herbig Ae/Be stars from spectral energy distributions and Gaia EDR3
• Fast Radial Flows in Transition Disk Holes
• 3D MHD Simulations of Planet Migration in Turbulent Stratified Disks
• On the accumulation of planetesimals near disc gaps created by protoplanets
• Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic Turbulence and Tangled Molecular Clouds
• The protoplanetary disk population in the rho-Ophiuchi region L1688 and the time evolution of Class II YSOs
• Evidence For A Vertical Dependence on the Pressure Structure in AS 209
• Dust-driven viscous ring-instability in protoplanetary disks
• Global Three-Dimensional Simulations of Outer Protoplanetary Disks with Ambipolar Diffusion
• 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
• Spontaneous ring formation in wind-emitting accretion discs
• Hints on the origins of particle traps in protoplanetary disks given by the $M_{\mathrm{dust}}-M_{\star }$ relation
• The Disc Miner I: A statistical framework to detect and quantify kinematical perturbations driven by young planets in discs
• Spiral Structure in the Gas Disk of TW Hya
• Efficient planet formation by pebble accretion in ALMA rings
• Midplane temperature and outer edge of the protoplanetary disk around HD 163296
• A dynamical measurement of the disk mass in Elias 2-27
• Directly tracing the vertical stratification of molecules in protoplanetary disks
• Hydro-, Magnetohydro-, and Dust-Gas Dynamics of Protoplanetary Disks
• Dynamical mass measurements of two protoplanetary discs
• Formation of rocky and icy planetesimals inside and outside the snow line: Effects of diffusion, sublimation and back-reaction
• The Disc Miner II: Revealing Gas substructures and Kinematic signatures from Planet-disc interaction through line profile analysis
• The theory of kinks -- I. A semi-analytic model of velocity perturbations due to planet-disc interaction
• A large population study of protoplanetary disks: Explaining the millimeter size-luminosity relation with or without sub-structure
• Interpreting high spatial resolution line observations of planet-forming disks with gaps and rings -- The case of HD 163296
• Rotation curves in protoplanetary disks with thermal stratification
• exoALMA III: Line-intensity Modeling and System Property Extraction from Protoplanetary Disks
• exoALMA V: Gaseous Emission Surfaces and Temperature Structures
• Mapping Protoplanetary Disk Vertical Structure with CO Isotopologue Line Emission
• 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
• Vortex-like kinematic signal, spirals, and beam smearing effect in the HD 142527 disk
• Survival of ALMA Rings in the Absence of Pressure Maxima
• Ring formation by coagulation of dust aggregates in early phase of disk evolution around a protostar
• The impact of dynamic pressure bumps on the observational properties of protoplanetary disks
• On the Origin of Dust Structures in Protoplanetary Disks: Constraints from the Rossby Wave Instability
• Properties of Density and Velocity Gaps Induced by a Planet in a Protoplanetary Disk
• exoALMA. XVII. Characterizing the Gas Dynamics around Dust Asymmetries
• Weighing protoplanetary discs with kinematics: physical model, method and benchmark
• exoALMA. VIII. Probabilistic Moment Maps and Data Products using Non-parametric Linear Models
• Planet-driven spirals in protoplanetary discs: limitations of the semi-analytical theory for observations

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• exoALMA III: Line-intensity Modeling and System Property Extraction from Protoplanetary Disks
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• The Circumbinary Disk of HD 34700A: I. CO gas kinematics indicate spirals, infall, and vortex motions
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• exoALMA XXIII. Estimating Disk and Planet Properties from Dust Morphologies with DBNets2.0
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• Reading between the rings: observed dust ring properties as probes of planet masses
• Gas dynamics around dust asymmetries in turbulent disks