Embedded Files
The exoALMA papers are published in Astrophysical Journal Letters exoALMA Focus Issue.
Below you will find all the papers with links to their ADS listing and a short summary of their main findings. A second wave of papers is expected in late 2025.
exoALMA I. Science Goals, Project Design and Data Products - Teague et al.
Presents an overview of the exoALMA program including how the observing program was developed and what makes this different to previous programs, such as the high spectral resolution of the data and the inclusion of ACA data for the largest sources. A summary of the main observations and the key findings from the first wave of papers is also presented.
exoALMA II. Data Calibration and Imaging Pipeline - Loomis et al.
This paper discusses the calibration and imaging methodologies applied to the exoALMA data including new approaches to the alignment of different execution blocks and tackling phase decoherence. All the calibration and imaging scripts produced as part of this paper are available from the Data page.
exoALMA III: Line-intensity Modeling and System Property Extraction from Protoplanetary Disks - Izquierdo et al.
In exoALMA III we present a methodology for studying the gaseous structure of our targets through channel-map analysis of 12CO, 13CO, and CS line emission. To gain insight into the physical, dynamical, and chemical processes shaping the exoALMA disks, our approach focuses on accurately identifying variations in the properties of these molecular lines across the wide range of geometrical configurations and projected morphologies in the sample. We also summarize key disk and stellar parameters derived from the channel-map analysis, including Keplerian masses, inclinations, and emission surface heights.
exoALMA IV. Substructures, Asymmetries, and the Faint Outer Disk in Continuum Emission - Curone et al.
exoALMA IV presents the continuum data, revealing substructures and peculiar features in the dust emission of each disk. We characterize the observed axisymmetric and non-axisymmetric substructures through a visibility space analysis. Most asymmetric disks show inner cavities and higher values of mass accretion rate and near-infrared excess, suggesting a connection between outer disk dust substructures and inner disk properties. We also examine the faint outer disk emission, finding that larger disks display a shallower falloff, while smaller disks have a sharper edge.
exoALMA V. Gaseous Emission Surfaces and Temperature Structures - Galloway-Sprietsma et al.
exoALMA V presents gaseous emission surfaces and peak intensity radial profiles for 12CO J=3-2, 13CO J=3-2, and CS J=7-6. We find that 12CO traces the upper disk atmosphere, while 13CO and CS probe layers closer to the midplane. We find that emission surface and intensity substructures are commonplace, often coincident across multiple molecular tracers, with several aligning with proposed planet locations. With the emission surfaces, we infer 2-D temperature profiles for nine disks. Four disks exhibit signs of photo-desorption, suggesting that this effect may be common even in low-FUV star-forming regions. We identify a linear relationship between emission height, disk mass, and surface density, indicating that emission height is inherently linked to these fundamental disk properties.
exoALMA VI. Rotating under Pressure: Rotation Curves, Azimuthal Velocity Substructures and Pressure Variations - Stadler et al.
Leveraging the high angular and spectral resolution of exoALMA, we can detect small-scale velocity perturbations in molecular line observations caused by local pressure variations in the disk, possibly induced by embedded protoplanets. This paper presents the rotational velocity and its deviations from Keplerian rotation (dvphi) for the exoALMA sample, as measured in the 12CO and 13CO emission lines. The rotation signatures show evidence for vertically stratified disks, in which 13CO rotates faster than 12CO due to a distinct thermal pressure gradient at their emitting heights. More than 75% of the rings and 80% of the gaps in the dust continuum emission resolved in dvphi are co-located with pressure maxima and minima, respectively. Additionally, pressure substructures are observed far beyond the dust continuum emission. Based on our findings, we conclude that pressure variations are likely the dominant mechanism for ring and gap formation in the dust continuum.
exoALMA VII. Benchmarking Hydrodynamics and Radiative Transfer Codes - Bae et al.
exoALMA VII presents comprehensive benchmark tests of hydrodynamics and radiative transfer codes that are widely used by the community. By carrying out hydrodynamic simulations of a protoplanetary disk with an embedded giant planet and comparing disk temperatures and synthetic CO emission, we demonstrate the robustness and consistency of these codes for forward-modeling and interpreting planet-driven kinematic perturbations.
exoALMA VIII. Probabilistic Moment Maps and Data Products Using Nonparametric Linear Models - Hilder et al.
Tantalising hints of ongoing planet formation in the exoALMA data, in the form of gas substructures, are found throughout the sample. Decoding these substructures is key to understanding the physical mechanisms at play. In this paper, we present a new image analysis tool built on nonparametric methods to extract information from the data in a statistically robust way, accounting for correlated noise in the images. We applied the method to the creation of moment maps, and found that it can effectively account for the bias induced in measurement of velocity perturbations associated with partially-resolved substructures. The method may be applied generally to any image analysis to provide probabilistic data products, and is applicable more broadly to any image subject to spatially correlated noise.
exoALMA IX. Regularized Maximum Likelihood Imaging of Non-Keplerian Features - Zawadzki et al.
exoALMA IX presents regularized maximum likelihood (RML) images of the gas emission for seven exoALMA targets exhibiting non-Keplerian features. These images independently confirm marginal features seen in the fiducial CLEAN images (including those likely caused by forming planets), and in some cases achieve super-resolution. We detail the procedure for applying RML imaging techniques to multi-channeled disk observations and compare with the corresponding CLEAN images, finding general agreement between the two methods.
exoALMA X. Channel Maps Reveal Complex 12CO Abundance Distributions and a Variety of Kinematic Structures with Evidence for Embedded Planets - Pinte et al.
Channel maps display striking kinematic substructures in 13 out of 15 protoplanetary disks, including spiral arms, velocity kinks, and filament-like features. Our analysis uncovers signatures of embedded planets in six disks, with estimated masses between 1 and 5 Jupiter masses at orbital distances of 80–330 au. Additionally, we detect the vertical CO snowline in disks with favorable inclinations, providing new insights into the balance between CO freeze-out and desorption in outer disk regions.
exoALMA XI. ALMA Observations and Hydrodynamic Models of LkCa 15: Implications for Planetary Mass Companions in the Dust Continuum Cavity - Gardener et al.
exoALMA XI focuses solely on LkCa 15, combining the high sensitivity observations of the exoALMA program with previously obtained high angular resolution data. The result is the closest look at LkCa 15 yet. Both dust continuum and 12CO observations are used to search for potential planetary companions in the dust continuum cavity. Though no clear indications of a planet’s presence are found observationally, hydrodynamic models allow for upper limits to be placed on planet masses should any exist. The models are inconsistent with massive planets clearing out a large cavity, but many low mass planets may be able to achieve a similar effect.
exoALMA XII. Weighing and Sizing exoALMA Disks with Rotation Curve Modeling - Longarini et al.
In this work, we model the rotation curves of the CO isotopologues 12CO and 13CO for ten sources in the exoALMA sample, constraining the stellar mass, disk mass, and density scale radius through a precise characterization of the pressure gradient and disk self-gravity. Our approach yields robust dynamical measurements of disk masses without relying on assumptions about disc composition, while also providing highly precise stellar mass estimates. These results offer crucial insights into the structure, composition, and evolution of protoplanetary disks.
exoALMA XIII. Gas Masses from N2H+ and C18O: A Comparison of Protoplanetary Gas Disk Mass Measurement Techniques - Trapman et al.
Presents ancillary N2H+ 3-2 observations of a ten disk subset of the exoALMA sample. These observations are combined with a large grid of thermochemical disk models models to derive gas disk masses based on integrated 13CO, C18O, and N2H+ line fluxes. The resulting gas masses are compared to the rotation curve based gas masses presented in exoALMA XII.
exoALMA XIV. Gas Surface Densities in the RXJ1604.3-2130 A Disk from Pressure-Broadened CO Line Wings - Yoshida et al.
The gas surface density profile is a key factor in understanding protoplanetary disks, yet it remains difficult to constrain. Recently, pressure broadening of spectral lines has been proposed as a sensitive probe of this property. This paper presents the first spatially resolved detection of pressure-broadened CO line wings in the RX J1604.3-2130 A disk, enabled by deep observations. By modeling the spectra, we robustly constrain the radial total gas surface density profile and find that a significant amount of gas is present, suggesting that planetary system formation is possible.
exoALMA XV. Interpreting the Height of CO Emission Layer - Rosotti et al.
The paper presents a model for molecular emission that links the emitting height of the CO molecule to the CO column and temperature structure. It then applies the model to a combined sample of sources from exoALMA and MAPS Large Programmes. The masses derived in this way are systematically lower than the values derived from the rotation curve if using an ISM CO abundance, implying that CO is depleted by a median factor ~20 with respect to the ISM value.
exoALMA XVI. Predicting Signatures of Large-Scale Turbulence in Protoplanetary Disks - Barraza-Alfaro et al.
We predicted the kinematic signatures from large-scale turbulent motions in mock exoALMA observations of 12CO(J:3-2) emission of protoplanetary disks. In our predictions, the large-scale turbulence driven by the vertical shear instability (VSI), the magneto-rotational instability (MRI) and the gravitational instability (GI) are observable in exoALMA quality data. We found that the VSI is unlikely to be active in the exoALMA sample, while the MRI and GI could drive some of the observed spiral-like kinematic substructures. Disks with smooth kinematic structure within the exoALMA sample indicate that they are nearly laminar.
exoALMA XVII. Characterizing the Gas Dynamics around Dust Asymmetries - Wölfer et al.
Studies the kinematics around azimuthal dust asymmetries observed in the disks of HD 135344B, HD 143006, HD 34282, and MWC 758 to search for signatures of dust-trapping vortices. The data are qualitatively compared to an analytical vortex model and hydrodynamic simulations of a vortex triggered at the edge of a dead zone and cavity edge created by a massive planet, repectively. While the observed substructures cannot unambiguously be linked to a vortex, HD 135344B exhibits similar features to that predicted by the models.
Page updated
Google Sites
Report abuse