A Highly Settled Disk around Oph163131 Villenave, M.; Stapelfeldt, K. R.; Duchêne, G. ...
The Astrophysical journal,
05/2022, Letnik:
930, Številka:
1
Journal Article
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Abstract
High dust density in the midplane of protoplanetary disks is favorable for efficient grain growth and can allow fast formation of planetesimals and planets, before disks dissipate. Vertical ...settling and dust trapping in pressure maxima are two mechanisms allowing dust to concentrate in geometrically thin and high-density regions. In this work, we aim to study these mechanisms in the highly inclined protoplanetary disk SSTC2D J163131.2-242627 (Oph 163131,
i
∼ 84°). We present new high-angular-resolution continuum and
12
CO ALMA observations of Oph 163131. The gas emission appears significantly more extended in the vertical and radial direction compared to the dust emission, consistent with vertical settling and possibly radial drift. In addition, the new continuum observations reveal two clear rings. The outer ring, located at ∼100 au, is well-resolved in the observations, allowing us to put stringent constraints on the vertical extent of millimeter dust particles. We model the disk using radiative transfer and find that the scale height of millimeter-sized grains is 0.5 au or less at 100 au from the central star. This value is about one order of magnitude smaller than the scale height of smaller micron-sized dust grains constrained by previous modeling, which implies that efficient settling of the large grains is occurring in the disk. When adopting a parametric dust settling prescription, we find that the observations are consistent with a turbulent viscosity coefficient of about
α
≲ 10
−5
at 100 au. Finally, we find that the thin dust scale height measured in Oph 163131 is favorable for planetary growth by pebble accretion: a 10
M
E
planet may grow within less than 10 Myr, even in orbits exceeding 50 au.
Abstract
As planets grow, the exchange of angular momentum with the gaseous component of the protoplanetary disc produces a net torque resulting in a variation of the semimajor axis of the planet. ...For low-mass planets not able to open a gap in the gaseous disc, this regime is known as type I migration. Pioneer works studied this mechanism in isothermal discs finding fast inward type I migration rates that were unable to reproduce the observed properties of extrasolar planets. In the last years, several improvements have been made in order to extend the study of type I migration rates to non-isothermal discs. Moreover, it was recently shown that if the planet’s luminosity due to solid accretion is taken into account, inward migration could be slowed down and even reversed. In this work, we study the planet formation process incorporating, and comparing, updated type I migration rates for non-isothermal discs and the role of planet’s luminosity over such rates. We find that the latter can have important effects on planetary evolution, producing a significant outward migration for the growing planets.
ABSTRACT
Misalignments within protoplanetary discs are now commonly observed, and features such as shadows in scattered light images indicate departure from a co-planar geometry. VLT/SPHERE (Very ...Large Telescope/Spectro-Polarimetric High-contrast Exoplanet REsearch) observations of the disc around HD 143006 show a large-scale asymmetry and two narrow dark lanes that are indicative of shadowing. ALMA (Atacama Large Millimeter/submillimeter Array) observations also reveal the presence of rings and gaps in the disc, along with a bright arc at large radii. We present new hydrodynamic simulations of HD 143006, and show that a configuration with both a strongly inclined binary and an outer planetary companion is the most plausible to explain the observed morphological features. We compute synthetic observations from our simulations, and successfully reproduce both the narrow shadows and the brightness asymmetry seen in infrared scattered light. Additionally, we reproduce the large dust observed in the mm continuum, due to a 10 Jupiter-mass planet detected in the CO kinematics. Our simulations also show the formation of a circumplanetary disc, which is misaligned with respect to the outer disc. The narrow shadows cast by the inner disc and the planet-induced ‘kink’ in the disc kinematics are both expected to move on a time-scale of ∼5–10 yr, presenting a potentially observable test of our model. If confirmed, HD 143006 would be the first known example of a circumbinary planet on a strongly misaligned orbit.
Dynamical studies suggest that most of the circumbinary discs (CBDs) should be coplanar. However, under certain initial conditions, the CBD can evolve toward polar orientation. Here we extend the ...parametric study of polar configurations around detached close-in binaries through N-body simulations. For polar configurations around binaries with mass ratios q below 0.7, the nominal location of the mean motion resonance (MMR) 1 : 4 predicts the limit of stability for eB > 0.1. Alternatively, for eB < 0.1 or q ∼ 1, the nominal location of the MMR 1 : 3 is the closest stable region. The presence of a giant planet increases the region of forbidden polar configurations around low mass ratio binaries with eccentricities eB∼ 0.4 with respect to rocky earth-like planets. For equal mass stars, the eccentricity excitation Δβ of polar orbits smoothly increases with decreasing distance to the binary. For q < 1, Δβ can reach values as high as 0.4. Finally, we studied polar configurations around HD 98800BaBb and show that the region of stability is strongly affected by the relative positions of the nodes. The most stable configurations in the system correspond to polar particles, which are not expected to survive on longer time-scales due to the presence of the external perturber HD 98800AaAb.
Context. Despite the recent discovery of spiral-shaped features in protoplanetary discs in the near-infrared and millimetre wavelengths, there is still an active discussion to understand how they ...formed. In fact, the spiral waves observed in discs around young stars can be due to different physical mechanisms: planet/companion torques, gravitational perturbations, or illumination effects. Aims. We study the spirals formed in the gaseous phase by two diametrically opposed shadows cast at fixed disc locations. The shadows are created by an inclined non-precessing disc inside the cavity, which is assumed to be optically thick. In particular, we analyse the effect of these spirals on the dynamics of the dust particles and discuss their detectability in transition discs. Methods. We performed gaseous hydrodynamical simulations with shadows, then we computed the dust evolution on top of the gaseous distribution, and finally we produced synthetic ALMA observations of the dust emission based on radiative transfer calculations. Results. Our main finding is that millimetre- to centimetre-sized dust particles are efficiently trapped inside the shadow-triggered spirals. We also observe that particles of various sizes starting at different stellocentric distances are well mixed inside these pressure maxima. This dynamical effect would favour grain growth and affect the resulting composition of planetesimals in the disc. In addition, our radiative transfer calculations show spiral patterns in the disc at 1.6 μm and 1.3 mm. Due to their faint thermal emission (compared to the bright inner regions of the disc) the spirals cannot be detected with ALMA. However, our synthetic observations prove that shadows are observable as dips in the thermal emission.
We present observations of the young multiple system UX Tauri to look for circumstellar disks and for signs of dynamical interactions. We obtained SPHERE/IRDIS deep differential polarization images ...in the
J
and
H
bands. We also used ALMA archival CO data. Large extended spirals are well detected in scattered light coming out of the disk of UX Tau A. The southern spiral forms a bridge between UX Tau A and C. These spirals, including the bridge connecting the two stars, all have a CO (3–2) counterpart seen by ALMA. The disk of UX Tau C is detected in scattered light. It is much smaller than the disk of UX Tau A and has a major axis along a different position angle, suggesting a misalignment. We performed
PHANTOM
SPH hydrodynamical models to interpret the data. The scattered light spirals, CO emission spirals and velocity patterns of the rotating disks, and the compactness of the disk of UX Tau C all point to a scenario in which UX Tau A has been perturbed very recently (∼1000 years) by the close passage of UX Tau C.
Photophoresis is a physical process based on momentum exchange between an illuminated dust particle and its gaseous environment. Its net effect in protoplanetary discs (PPD) is the outward transport ...of solid bodies from hot to cold regions. This process naturally leads to the formation of ring-shaped features where dust piles up. In this work, we study the dynamical effects of photophoresis in PPD by including the photophoretic force in the two-fluid (gas+dust) smoothed particle hydrodynamics (SPH) code developed by Barrière-Fouchet et al. (2005). We find that the conditions of pressure and temperature encountered in the inner regions of PPD result in important photophoretic forces, which dramatically affect the radial motion of solid bodies. Moreover, dust particles have different equilibrium locations in the disc depending on their size and their intrinsic density. The radial transport towards the outer parts of the disc is more efficient for silicates than for iron particles, which has important implications for meteoritic composition. Our results indicate that photophoresis must be taken into account in the inner regions of PPD to fully understand the dynamics and the evolution of the dust composition.
ABSTRACT
More than 50 per cent of solar-mass stars form in multiple systems. It is therefore crucial to investigate how multiplicity affects the star and planet formation processes at the ...protostellar stage. We report continuum and C18O (2–1) observations of the VLA 1623–2417 protostellar system at 50 au angular resolution as part of the ALMA (Atacama Large Millimeter/submillimeter Array) Large Program FAUST. The 1.3 mm continuum probes the discs of VLA 1623A, B, and W, and the circumbinary disc of the A1 + A2 binary. The C18O emission reveals, for the first time, the gas in the disc envelope of VLA 1623W. We estimate the dynamical mass of VLA 1623W, Mdyn = 0.45 ± 0.08 M⊙, and the mass of its disc, Mdisc ∼ 6 × 10−3 M⊙. C18O also reveals streamers that extend up to 1000 au, spatially and kinematically connecting the envelope and outflow cavities of the A1 + A2 + B system with the disc of VLA 1623W. The presence of the streamers, as well as the spatial (∼1300 au) and velocity (∼2.2 km s−1) offsets of VLA 1623W, suggests that either sources W and A + B formed in different cores, interacting between them, or source W has been ejected from the VLA 1623 multiple system during its formation. In the latter case, the streamers may funnel material from the envelope and cavities of VLA 1623AB on to VLA 1623W, thus concurring to set its final mass and chemical content.
ABSTRACT
The ALMA interferometer has played a key role in revealing a new component of the Sun-like star forming process: the molecular streamers, i.e. structures up to thousands of au long ...funnelling material non-axisymmetrically to discs. In the context of the FAUST ALMA LP, the archetypical VLA1623-2417 protostellar cluster has been imaged at 1.3 mm in the SO(56–45), SO(66–55), and SiO(5–4) line emission at the spatial resolution of 50 au. We detect extended SO emission, peaking towards the A and B protostars. Emission blue-shifted down to 6.6 km s−1 reveals for the first time a long (∼ 2000 au) accelerating streamer plausibly feeding the VLA1623 B protostar. Using SO, we derive for the first time an estimate of the excitation temperature of an accreting streamer: 33 ± 9 K. The SO column density is ∼ 1014 cm−2, and the SO/H2 abundance ratio is ∼ 10−8. The total mass of the streamer is 3 × 10−3M⊙, while its accretion rate is 3–5 × 10−7M⊙ yr−1. This is close to the mass accretion rate of VLA1623 B, in the 0.6–3 × 10−7M⊙ yr−1 range, showing the importance of the streamer in contributing to the mass of protostellar discs. The highest blue- and red-shifted SO velocities behave as the SiO(5–4) emission, the latter species detected for the first time in VLA1623-2417: the emission is compact (100–200 au), and associated only with the B protostar. The SO excitation temperature is ∼ 100 K, supporting the occurrence of shocks associated with the jet, traced by SiO.
ABSTRACT
Stellar binaries represent a substantial fraction of stellar systems, especially among young stellar objects. Accordingly, binaries play an important role in setting the architecture of a ...large number of protoplanetary discs. Binaries in coplanar and polar orientations with respect to the circumbinary disc are stable configurations and could induce non-axisymmetric structures in the dust and gas distributions. In this work, we suggest that the structures shown in the central region of the protoplanetary disc HD 169142 are produced by the presence of an inner stellar binary and a circumbinary (P-type) planet. We find that a companion with a mass ratio of 0.1, semimajor axis of 9.9 au, eccentricity of 0.2, and inclination of 90°, together with a 2 MJ coplanar planet on a circular orbit at 45 au reproduce the structures at the innermost ring observed at 1.3 mm and the shape of spiral features in scattered light observations. The model predicts changes in the disc’s dust structure, and star’s astrometric parameters, which would allow testing its veracity by monitoring this system over the next 20 yr.
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