Abstract
We explore the dynamical structure of the protoplanetary disks surrounding HD 163296 and MWC 480 as part of the Molecules with ALMA at Planet-forming Scales (MAPS) large program. Using the
J
...= 2–1 transitions of
12
CO,
13
CO, and C
18
O imaged at spatial resolutions of ∼0.″15 and with a channel spacing of 200 m s
−1
, we find perturbations from Keplerian rotation in the projected velocity fields of both disks (≲5% of the local Keplerian velocity), suggestive of large-scale (tens of astronomical units in size), coherent flows. By accounting for the azimuthal dependence on the projection of the velocity field, the velocity fields were decomposed into azimuthally averaged orthogonal components,
v
ϕ
,
v
r
, and
v
z
. Using the optically thick
12
CO emission as a probe of the gas temperature, local variations of ≈3 K (≈5% relative changes) were observed and found to be associated with the kinematic substructures. The MWC 480 disk hosts a suite of tightly wound spiral arms. The spirals arms, in conjunction with the highly localized perturbations in the gas velocity structure (kinematic planetary signatures), indicate a giant planet, ∼1
M
Jup
, at a radius of ≈245 au. In the disk of HD 163296, the kinematic substructures were consistent with previous studies of Pinte et al. and Teague et al. advocating for multiple ∼1
M
Jup
planets embedded in the disk. These results demonstrate that molecular line observations that characterize the dynamical structure of disks can be used to search for the signatures of embedded planets. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Investigating the dynamical evolution of dust grains in proto-planetary disks is a key issue to understand how planets should form. We identify under which conditions dust settling can be constrained ...by high angular resolution ALMA observations at mm wavelengths, and which observational strategies are suited for such studies. We find out that an angular resolution better than or equal to " 0.1" (using 2.3 km baselines at 0.8mm) allows us to constrain the dust scale height and flaring index with sufficient precision to unambiguously distinguish between settled and non-settled disks, provided the inclination is close enough to edge-on (i > 75degrees). Ignoring dust settling and assuming hydrostatic equilibrium when analyzing such disks biase the derived dust temperature, the radial dependency of the dust emissivity index and the surface density distribution.
Abstract
While protoplanetary disks are often treated as isolated systems in planet formation models, observations increasingly suggest that vigorous interactions between Class II disks and their ...environments are not rare. DO Tau is a T Tauri star that has previously been hypothesized to have undergone a close encounter with the HV Tau system. As part of the DESTINYS ESO Large Programme, we present new Very Large Telescope (VLT)/SPHERE polarimetric observations of DO Tau and combine them with archival Hubble Space Telescope (HST) scattered-light images and Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO isotopologues and CS to map a network of complex structures. The SPHERE and ALMA observations show that the circumstellar disk is connected to arms extending out to several hundred astronomical units. HST and ALMA also reveal stream-like structures northeast of DO Tau, some of which are at least several thousand astronomical units long. These streams appear not to be gravitationally bound to DO Tau, and comparisons with previous Herschel far-IR observations suggest that the streams are part of a bridge-like structure connecting DO Tau and HV Tau. We also detect a fainter redshifted counterpart to a previously known blueshifted CO outflow. While some of DO Tau’s complex structures could be attributed to a recent disk–disk encounter, they might be explained alternatively by interactions with remnant material from the star formation process. These panchromatic observations of DO Tau highlight the need to contextualize the evolution of Class II disks by examining processes occurring over a wide range of size scales.
Turbulent motions are believed to regulate angular momentum transport and influence dust evolution in protoplanetary disks. Measuring the strength of turbulence is challenging through gas line ...observations because of the requirement for high spatial and spectral resolution data, and an exquisite determination of the temperature. In this work, taking the well-known HD 163296 disk as an example, we investigated the contrast of gaps identified in high angular resolution continuum images as a probe for the level of turbulence. With self-consistent radiative transfer models, we simultaneously analyzed the radial brightness profiles along the disk major and minor axes, and the azimuthal brightness profiles of the B67 and B100 rings. By fitting all the gap contrasts measured from these profiles, we constrained the gas-to-dust scale height ratio Λ to be 3.0
−0.8
+0.3
, 1.2
−0.1
+0.1
, and ≥ 6.5 for the D48, B67, and B100 regions, respectively. The varying gas-to-dust scale height ratios indicate that the degree of dust settling changes with radius. The inferred values for Λ translate into a turbulence level of
α
turb
< 3 × 10
−3
in the D48 and B100 regions, which is consistent with previous upper limits set by gas line observations. However, turbulent motions in the B67 ring are strong with
α
turb
∼ 1.2 × 10
−2
. Due to the degeneracy between Λ and the depth of dust surface density drops, the turbulence strength in the D86 gap region is not constrained.
ABSTRACT We aim to unveil the observational imprint of physical mechanisms that govern planetary formation in the young, multiple system GG Tau A. We present ALMA observations of 12CO and 13CO 3-2 ...and 0.9 mm continuum emission with 0 35 resolution. The 12CO 3-2 emission, found within the cavity of the circumternary dust ring (at radius <180 au) where no 13CO emission is detected, confirms the presence of CO gas near the circumstellar disk of GG Tau Aa. The outer disk and the recently detected hot spot lying at the outer edge of the dust ring are mapped both in 12CO and 13CO. The gas emission in the outer disk can be radially decomposed as a series of slightly overlapping Gaussian rings, suggesting the presence of unresolved gaps or dips. The dip closest to the disk center lies at a radius very close to the hot spot location at ∼250-260 au. The CO excitation conditions indicate that the outer disk remains in the shadow of the ring. The hot spot probably results from local heating processes. The two latter points reinforce the hypothesis that the hot spot is created by an embedded proto-planet shepherding the outer disk.
Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary (CB) disks may ...be in the midst of planet formation. However, there are very few CB disks detected. The streaming gas accreting from the CB ring toward the CS disks and possible outflows are also identified and resolved. The SO emission is found to be at the bases of the streaming shocks. Our results suggest that the UY Aur system is undergoing an active accretion phase from the CB disk to the CS disks. The UY Aur B might also be a binary system, making the UY Aur a triple system.
The origin of the very red optical and infrared colours of intermediate-age (~10-500 Myr) L-type dwarfs remains unknown. It has been suggested that low-gravity atmospheres containing large amounts of ...dust may account for the observed reddish nature. We explored an alternative scenario by simulating debris disc around G 196-3 B, which is an L3 young brown dwarf with a mass of ~15 M sub( Jup) and an age in the interval 20-300 Myr. The best-fit solution to G 196-3 B's photometric spectral energy distribution from optical wavelengths through 24 ...m corresponds to the combination of an unreddened L3 atmosphere (T sub( eff) ... 1870 K) and a warm (...1280 K), narrow (...0.07-0.11 R...) debris disc located at very close distances (...0.12-0.20 R...) from the central brown dwarf. This putative, optically thick, dusty belt, whose presence is compatible with the relatively young system age, would have a mass greater than or equal to 7 x 10 super( -10) M... comprised of submicron/micron characteristic dusty particles with temperatures close to the sublimation threshold of silicates. Considering the derived global properties of the belt and the disc-to-brown dwarf mass ratio, the dusty ring around G 196-3 B may resemble the rings of Neptune and Jupiter, except for its high temperature and thick vertical height (...6 x 10 super( 3) km). Our inferred debris disc model is able to reproduce G 196-3 B's spectral energy distribution to a satisfactory level of achievement. (ProQuest: ... denotes formulae/symbols omitted.)
We present Atacama Large Millimeter and Submillimeter Array observations of the protoplanetary disk around the Herbig Ae star HD 163296 that trace the spatial distribution of millimeter-sized ...particles and cold molecular gas on spatial scales as small as 25 astronomical units (A.U.). The image of the disk recorded in the 1.3 mm continuum emission reveals three dark concentric rings that indicate the presence of dust depleted gaps at about 60, 100, and 160 A.U. from the central star. The maps of the 12CO, 13CO, and C18O J = 2 - 1 emission do not show such structures but reveal a change in the slope of the radial intensity profile across the positions of the dark rings in the continuum image. By comparing the observations with theoretical models for the disk emission, we find that the density of CO molecules is reduced inside the middle and outer dust gaps. However, in the inner ring there is no evidence of CO depletion. From the measurements of the dust and gas densities, we deduce that the gas-to-dust ratio varies across the disk and, in particular, it increases by at least a factor 5 within the inner dust gap compared to adjacent regions of the disk. The depletion of both dust and gas suggests that the middle and outer rings could be due to the gravitational torque exerted by two Saturn-mass planets orbiting at 100 and 160 A.U. from the star. On the other hand, the inner dust gap could result from dust accumulation at the edge of a magnetorotational instability dead zone, or from dust opacity variations at the edge of the CO frost line. Observations of the dust emission at higher angular resolution and of molecules that probe dense gas are required to establish more precisely the origins of the dark rings observed in the HD 163296 disk.
Les étoiles, durant les premiers millions d’années de leur existence, sont entourées d’un disque composé à 99% de gaz et à 1 % de poussière. La poussière est initialement sous forme de grains de ...taille sub-micrométrique mais évolue jusqu’à pouvoir former les planètes. Grâce à l’interféromètre du plateau de Bure, avec lequel nous avons observé aux longueurs d’onde millimétrique, l’évolution temporelle ainsi que la distribution radiale des grains de poussière a pu être mise en évidence sur de nombreux disques. Par ailleurs, l’important gain en résolution et sensibilité d’ALMA, un nouvel interféromètre très performant basé au Chili, a nécessité l’amélioration de notre code de transfert radiatif afin de déterminer si et comment il allait être possible d’observer la sédimentation de la poussière, étape préalable à la formation des planétésimaux.
The stars, during the first millions years of their existence, are surrounded by a protoplanetary disk composed of99 % of gas and of 1 % of dust. The dust is initially under the form of sub-micrometric grains but evolves to likelyform planets. Thanks to the Plateau de Bure interferometer, with whom we observed at the millimeter wavelengths, the temporal evolution as well the radial distribution of the dust grains has been bringing to light in several disks.In addition, the important gain in resolution and in sensibility of ALMA, a new interferometer based in Chili, has required the improvement of our transfert radiativ code in order to determine if and how it will be possible to observe the dust settling, preliminary step for the formation of planetesimals.
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