We present the first kinematical detection of embedded protoplanets within a protoplanetary disk. Using archival ALMA observations of HD 163296, we demonstrate a new technique to measure the rotation curves of CO isotopologue emission to sub-percent precision relative to the Keplerian rotation. These rotation curves betray substantial deviations caused by local perturbations in the radial pressure gradient, likely driven by gaps carved in the gas surface density by Jupiter-mass planets. Comparison with hydrodynamic simulations shows excellent agreement with the gas rotation profile when the disk surface density is perturbed by two Jupiter mass planets at 83 au and 137 au. As the rotation of the gas is dependent on the pressure of the total gas component, this method provides a unique probe of the gas surface density profile without incurring significant uncertainties due to gas-to-dust ratios or local chemical abundances which plague other methods. Future analyses combining both methods promise to provide the most accurate and robust measures of embedded planetary mass. Furthermore, this method provides a unique opportunity to explore wide-separation planets beyond the mm continuum edge and to trace the gas pressure profile essential in modelling grain evolution in disks.

Context. Imaged in the gap of a transition disk and found at a separation of about 195 mas (∼22 au) from its host star at a position angle of about 155 o , PDS 70 b is the most robustly detected young planet to date. This system is therefore a unique laboratory for characterizing the properties of young planetary systems at the stage of their formation. Aims. We aim to trace direct and indirect imprints of PDS 70 b on the gas and dust emission of the circumstellar disk in order to study the properties of this ∼5 Myr young planetary system. Methods. We obtained ALMA band 7 observations of PDS 70 in dust continuum and 12 CO (3 − 2) and combined them with archival data. This resulted in an unprecedented angular resolution of about 70 mas (∼8 au). Results. We derive an upper limit on circumplanetary material at the location of PDS 70 b of ∼0.01 M ⊕ and find a highly structured circumstellar disk in both dust and gas. The outer dust ring peaks at 0.65 (74 au) and reveals a possible second unresolved peak at about 0.53 (60 au). The integrated intensity of CO also shows evidence of a depletion of emission at ∼0.2 (23 au) with a width of ∼0.1 (11 au). The gas kinematics show evidence of a deviation from Keplerian rotation inside 0.8 (91 au). This implies a pressure gradient that can account for the location of the dust ring well beyond the location of PDS 70 b. Farther in, we detect an inner disk that appears to be connected to the outer disk by a possible bridge feature in the northwest region in both gas and dust. We compare the observations to hydrodynamical simulations that include a planet with different masses that cover the estimated mass range that was previously derived from near-infrared photometry (∼5-9 M Jup ). We find that even a planet with a mass of 10 M Jup may not be sufficient to explain the extent of the wide gap, and an additional low-mass companion may be needed to account for the observed disk morphology.

Protoplanetary disks are known to posses a stunning variety of substructure in the distribution of their mm sized grains, predominantly seen as rings and gaps 1 , which are frequently interpreted as due to the shepherding of large grains by either hidden, still-forming planets within the disk 2 or (magneto-)hydrodynamic instabilities 3 . The velocity structure of the gas offers a unique probe of both the underlying mechanisms driving the evolution of the disk, the presence of embedded planets and characterising the transportation of material within the disk, such as following planet-building material from volatile-rich regions to the chemically-inert midplane, or detailing the required removal of angular momentum. Here we present the radial profiles of the three velocity components of gas in upper disk layers in the disk of HD 163296 as traced by 12 CO molecular emission. These velocities reveal significant flows from the disk surface towards the midplane of disk at the radial locations of gaps argued to be opened by embedded planets 4-7 , bearing striking resemblance to meridional flows, long predicted to occur during the early stages of planet formation [8][9][10][11] . In addition, a persistent radial outflow is seen at the outer edge of the disk, potentially the base of a wind associated with previously detected extended emission 12 .We use observations of 12 CO J = 2−1 emission from HD 163296 to measure the 3D velocities structure of the gas. These data were originally presented as part of the Disk Substructures at High Angular Resolution Project (DSHARP) Atacama Large Millimeter/submillimeter Array (ALMA) large program 1, 5 , which combined previously analysed lower spatial resolution data 4, 13 . The disk around HD 163296 is known to host multiple rings of large mm sized grains trapped within regions of gas pressure maxima 6 , with a depletion of the gas within the dust gaps 4 , highly suggestive of a planetary origin. In the outer disk, at a radius of ≈ 260 au (where an astronomical unit, au, is the distance between the Earth and the Sun), a local disturbance in the velocity field is likely driven by a massive, 2 MJup planet (where MJup is the mass of Jupiter), deeply embedded within the disk 7 .To improve the signal to noise and achieve high velocity precision we first radially bin the spectral data 6 . As 12 CO J = 2 − 1 is optically thick, the τ ≈ 1 surface traces a region typically 2 -4 pressure scale heights above the disk midplane, resulting in asymmetries in the observed emission profiles which must be taken into account when radially binning the data 5,14,15 . This is most clearly seen in a map of the line center, shown in the left panel of Fig. 1, which deviates significantly from the symmetric dipole pattern found in geometrically thin disks. As Keplerian rotation dominates the velocity structure, a parametric emission surface can be inferred which correctly accounts for this projection effect, with the best-fit surface shown in Fig. 1. This approach finds an emission surface consistent with ano...

We present the discovery of a spatially unresolved source of sub-millimeter continuum emission (λ = 855 µm) associated with a young planet, PDS 70 c, recently detected in Hα emission around the 5 Myr old T Tauri star PDS 70. We interpret the emission as originating from a dusty circumplanetary disk with a dust mass between 2×10 −3 M ⊕ and 4.2×10 −3 M ⊕ . Assuming a standard gas-to-dust ratio of 100, the ratio between the total mass of the circumplanetary disk and the mass of the central planet would be between 10 −4 − 10 −5 . Furthermore, we report the discovery of another compact continuum source located 0.074 ± 0.013 South-West of a second known planet in this system, PDS 70 b, that was previously detected in near-infrared images. We speculate that the latter source might trace dust orbiting in proximity of the planet, but more sensitive observations are required to unveil its nature.

PDS 70 is a unique system in which two protoplanets, PDS 70 b and c, have been discovered within the dustdepleted cavity of their disk, at ∼22 and 34 au, respectively, by direct imaging at infrared wavelengths. Subsequent detection of the planets in the Hα line indicates that they are still accreting material through circumplanetary disks.In this Letter, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855 μm at high angular resolution (∼20 mas, 2.3 au) that aim to resolve the circumplanetary disks and constrain their dust masses. Our observations confirm the presence of a compact source of emission colocated with PDS 70 c, spatially separated from the circumstellar disk and less extended than ∼1.2 au in radius, a value close to the expected truncation radius of the circumplanetary disk at a third of the Hill radius. The emission around PDS 70 c has a peak intensity of ∼86 ± 16 μJy beam −1 , which corresponds to a dust mass of ∼0.031 M ⊕ or ∼0.007 M ⊕ , assuming that it is only constituted of 1 μm or 1 mm sized grains, respectively. We also detect extended, low surface brightness continuum emission within the cavity near PDS 70 b. We observe an optically thin inner disk within 18 au of the star with an emission that could result from small micron-sized grains transported from the outer disk through the orbits of b and c. In addition, we find that the outer disk resolves into a narrow and bright ring with a faint inner shoulder.

Here we present high-resolution (15-24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) ALMA Large Program. Our analysis employs observations of the (J = 2-1) and (1-0) lines of 13 CO and C 18 O and the (J = 1-0) line of C 17 O for five protoplanetary disks. We retrieve CO gas density distributions, using three independent methods: (1) a thermochemical modeling framework based on the CO data, the broadband spectral energy distribution, and the millimeter continuum emission; (2) an empirical temperature distribution based on optically thick CO lines; and (3) a direct fit to the C 17 O hyperfine lines. Results from these methods generally show excellent agreement. The CO gas column density profiles of the five disks show significant variations in the absolute value and the radial shape. Assuming a gas-to-dust mass ratio of 100, all five disks have a global CO-to-H 2 abundance 10-100 times lower than the interstellar medium ratio. The CO gas distributions between 150 and 400 au match well with models of viscous disks, supporting the longstanding theory. CO gas gaps appear to be correlated with continuum gap locations, but some deep continuum gaps do not have corresponding CO gaps. The relative depths of CO and dust gaps are generally consistent with predictions of planet-disk interactions, but some CO gaps are 5-10 times shallower than predictions based on dust gaps. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.

We present the first images of the transition disk around the close binary system HD 34700A in polarized scattered light using the Gemini Planet Imager instrument on Gemini South. The J and H band images reveal multiple spiral-arm structures outside a large (R = 0.49 = 175 au) cavity along with a bluish spiral structure inside the cavity. The cavity wall shows a strong discontinuity and we clearly see significant non-azimuthal polarization U φ consistent with multiple scattering within a disk at an inferred inclination ∼42 • . Radiative transfer modeling along with a new Gaia distance suggest HD 37400A is a young (∼5 Myr) system consisting of two intermediate-mass (∼2 M ) stars surrounded by a transitional disk and not a solar-mass binary with a debris disk as previously classified. Conventional assumptions of the dust-to-gas ratio would rule out a gravitational instability origin to the spirals while hydrodynamical models using the known external companion or a hypothetical massive protoplanet in the cavity both have trouble reproducing the relatively large spiral arm pitch angles (∼ 30 • ) without fine tuning of gas temperature. We explore the possibility that material surrounding a massive protoplanet could explain the rim discontinuity after also considering effects of shadowing by an inner disk. Analysis of archival Hubble Space Telescope data suggests the disk is rotating counterclockwise as expected from the spiral arm structure and revealed a new low-mass companion at 6.45 separation. We include an appendix which sets out clear definitions of Q, U, Q φ , U φ , correcting some confusion and errors in the literature.

We improve on our previous treatments of long-term evolution of protostellar disks by explicitly solving disk self-gravity in two dimensions. The current model is an extension of the one-dimensional layered accretion disk model of Bae et al. We find that gravitational instability (GI)-induced spiral density waves heat disks via compressional heating (i.e. P dV work), and can trigger accretion outbursts by activating the magnetorotational instability (MRI) in the magnetically inert disk deadzone. The GI-induced spiral waves propagate well inside of gravitationally unstable region before they trigger outbursts at R 1 AU where GI cannot be sustained. This long-range propagation of waves cannot be reproduced with the previously used local α treatments for GI. In our standard model where zero dead-zone residual viscosity (α rd ) is assumed, the GI-induced stress measured at the onset of outbursts is locally as large as 0.01 in terms of the generic α parameter. However, as suggested in our previous one-dimensional calculations, we confirm that the presence of a small but finite α rd triggers thermally-driven bursts of accretion instead of the GI + MRI-driven outbursts that are observed when α rd = 0. The inclusion of non-zero residual viscosity in the dead-zone decreases the importance of GI soon after mass feeding from the envelope cloud ceases. During the infall phase while the central protostar is still embedded, our models stay in a "quiescent" accretion phase witḣ M acc ∼ 10 −8 − 10 −7 M ⊙ yr −1 over 60 % of the time and spend less than 15 % of the infall phase in accretion outbursts. While our models indicate that episodic mass accretion during protostellar evolution can qualitatively help explain the low accretion luminosities seen in most low-mass protostars, detailed tests of the mechanism will require model calculations for a range of protostellar masses with some constraint on the initial core angular momentum, which affects the length of time spent in a quasi-steady disk accretion phase.