IMAGING THE INNER AND OUTER GAPS OF THE PRE-TRANSITIONAL DISK OF HD 169142 AT 7 mm

The protoplanetary system HD 169142 is one of the few cases where a potential candidate protoplanet has recently been detected by direct imaging in the near-infrared. To study the interaction between the protoplanet and the disk itself, observations of the gas and dust surface density structure are needed. This paper reports new ALMA observations of the dust continuum at 1.3 mm, 12 CO, 13 CO, and C 18 O J = 2−1 emission from the system HD 169142 (which is observed almost face-on) at an angular resolution of ∼0 . 3 × 0 . 2 (∼35 × 20 au). The dust continuum emission reveals a double-ring structure with an inner ring between 0 . 17−0 . 28 (∼20−35 au) and an outer ring between 0 . 48−0 . 64 (∼56−83 au). The size and position of the inner ring is in good agreement with previous polarimetric observations in the near-infrared and is consistent with dust trapping by a massive planet. No dust emission is detected inside the inner dust cavity (R 20 au) or within the dust gap (∼35−56 au) down to the noise level. In contrast, the channel maps of the J = 2−1 line of the three CO isotopologs reveal gas inside the dust cavity and dust gap. The gaseous disk is also much larger than the compact dust emission; it extends to ∼1 . 5 (∼180 au) in radius. This difference and the sharp drop of the continuum emission at large radii point to radial drift of large dust grains (>µm size). Using the thermo-chemical disk code dali, we modeled the continuum and the CO isotopolog emission to quantitatively measure the gas and dust surface densities. The resulting gas surface density is reduced by a factor of ∼30−40 inward of the dust gap. The gas and dust distribution indicate that two giant planets shape the disk structure through dynamical clearing (dust cavity and gap) and dust trapping (double-ring dust distribution).

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“…28−0 . 48, confirming the earlier findings of Osorio et al (2014). The dust continuum emission drops steeply beyond 0 .…”

Section: Dust Continuum Emissionsupporting

confidence: 84%

“…17 (20 au) from the star. The dust ring seen in scattered light is also detected in the 7 mm continuum by Osorio et al (2014). The latter find evidence of a second dust gap beyond the inner ring.…”

Section: Hd 169142mentioning

confidence: 72%

ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets

Fedele

Carney

Hogerheijde

et al. 2017

A&A

222

243

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“…A narrow gap around 50 AU was first discovered in H-band VLT/NACO polarized light imaging (Quanz et al 2013), and subsequently found by Subaru/HiCIAO (Momose et al 2015) and in dust thermal emission at 7mm by VLA (Osorio et al 2014). The radius-varying disk profile was interpreted as two power laws in the inner and outer disks joined by a transition region in between by Momose et al (2015).…”

Section: Hd 169142mentioning

confidence: 89%

What is the Mass of a Gap-opening Planet?

Dong

Fung

2017

ApJ

118

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High contrast imaging instruments such as GPI and SPHERE are discovering gap structures in protoplanetary disks at an ever faster pace. Some of these gaps may be opened by planets forming in the disks. In order to constrain planet formation models using disk observations, it is crucial to find a robust way to quantitatively back out the properties of the gap-opening planets, in particular their masses, from the observed gap properties, such as their depths and widths. Combing 2D and 3D hydrodynamics simulations with 3D radiative transfer simulations, we investigate the morphology of planet-opened gaps in near-infrared scattered light images. Quantitatively, we obtain correlations that directly link intrinsic gap depths and widths in the gas surface density to observed depths and widths in images of disks at modest inclinations under finite angular resolution. Subsequently, the properties of the surface density gaps enable us to derive the disk scale height at the location of the gap h, and to constrain the quantity M 2 p /α, where M p is the mass of the gap-opening planet and α characterizes the viscosity in the gap. As examples, we examine the gaps recently imaged by VLT/SPHERE, Gemini/GPI, and Subaru/HiCIAO in HD 97048, TW Hya, HD 169142, LkCa 15, and RX J1615.3-3255. Scale heights of the disks and possible masses of the gap-opening planets are derived assuming each gap is opened by a single planet. Assuming α = 10 −3 , the derived planet mass in all cases are roughly between 0.1-1 M J .

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“…In particular, we investigate the possibility of having a smooth distribution of micron size particles over the entire disk and a large cavity in millimetre grains, as recently observed in transition disks, such as e.g. SR 21 (Follette et al 2013;Pérez et al 2014), HD 169142 (Osorio et al 2014), and MWC 758. (Andrews et al 2011;Grady et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Gas and dust structures in protoplanetary disks hosting multiple planets

Pinilla

Ovelar

Ataiee

et al. 2014

A&A

106

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Context. Transition disks have dust-depleted inner regions and may represent an intermediate step of an on-going disk dispersal process, where planet formation is probably in progress. Recent millimetre observations of transition disks reveal radially and azimuthally asymmetric structures, where micron-and millimetre-sized dust particles may not spatially coexist. These properties can be the result of particle trapping and grain growth in pressure bumps originating from the disk interaction with a planetary companion. The multiple features observed in some transition disks, such as SR 21, suggest the presence of more than one planet. Aims. We aim to study the gas and dust distributions of a disk hosting two massive planets as a function of different disk and dust parameters. Observational signatures, such as spectral energy distributions, sub-millimetre, and polarised images, are simulated for various parameters. Methods. Two dimensional hydrodynamical and one dimensional dust evolution numerical simulations are performed for a disk interacting with two massive planets. Adopting the previously determined dust distribution, and assuming an axisymmetric disk model, radiative transfer simulations are used to produce spectral energy distributions and synthetic images in polarised intensity at 1.6 µm and sub-millimetre wavelengths (850 µm). We analyse possible scenarios that can lead to gas azimuthal asymmetries. Results. We confirm that planets can lead to particle trapping, although for a disk with high viscosity (α turb = 10 −2 ), the planet should be more massive than 5 M Jup and dust fragmentation should occur with low efficiency (v f ∼ 30 m s −1 ). This will lead to a ring-like feature as observed in transition disks in the millimetre. When trapping occurs, we find that a smooth distribution of micron-sized grains throughout the disk, sometimes observed in scattered light, can only happen if the combination of planet mass and turbulence is such that small grains are not fully filtered out. A high disk viscosity (α turb = 10 −2 ) ensures a replenishment of the cavity in micron-sized dust, while for lower viscosity (α turb = 10 −3 ), the planet mass is constrained to be less than 5 M Jup . In these cases, the gas distribution is likely to show low-amplitude azimuthal asymmetries caused by disk eccentricity rather than by long-lived vortices.

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IMAGING THE INNER AND OUTER GAPS OF THE PRE-TRANSITIONAL DISK OF HD 169142 AT 7 mm

Cited by 91 publications

References 40 publications

ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets

ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets

What is the Mass of a Gap-opening Planet?

Gas and dust structures in protoplanetary disks hosting multiple planets

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