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

By D. Fedele, M. Carney, M. Hogerheijde, C. Walsh, A. Miotello, P. Klaassen, Simon Bruderer, Th. Henning, E. I. Observatory, L. I. O. Physics and 3 more. 2017

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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 ~\hbox{$0\farcs3 \,\times\, 0\farcs2$} (~35 × 20 au). The dust continuum emission reveals a double-ring structure with an inner ring between \hbox{$0\farcs17{-}0\farcs28$} (~20−35 au) and an outer ring between \hbox{$0\farcs48{-}0\farcs64$} (~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\hbox{$\farcs5$} (~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 (> μ m 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).

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/57342722b7cc829b9e1a4d179eb2b5bb352fdfab

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Citations in the corpus

Molecules with ALMA at Planet-forming Scales (MAPS). I. Program Overview and Highlights (2021, background): “The observed gaps have often been connected to ongoing planet formation (e.g., Flock et al. 2015; Fedele et al. 2017; Keppler et al. 2019), though other plausible explanations exist as well (see Andrews 2020, for a review).”
The Disk Substructures at High Angular Resolution Project (DSHARP). I. Motivation, Sample, Calibration, and Overview (2018, background): “…including azimuthal asymmetries (Casassus et al. 2013; van der Marel et al. 2013; Isella et al. 2013; Pérez et al. 2014), additional rings (Fedele et al. 2017; van der Plas et al. 2017), warped geometries (and/or radial inflows; Rosenfeld et al. 2012, 2014; Marino et al. 2015; Casassus…”
The Disk Substructures at High Angular Resolution Project (DSHARP). V. Interpreting ALMA Maps of Protoplanetary Disks in Terms of a Dust Model (2018, background): “…that protoplanetary disks do not have simple monotonically decreasing surface density profiles, but consist of multiple narrow rings (e.g., ALMA Partnership et al. 2015; Andrews et al. 2016; Isella et al. 2016; Fedele et al. 2017, 2018; Huang et al. 2018), apparently single mas- ar X iv :1 81 2.”
ALMA continuum observations of the protoplanetary disk AS 209. Evidence of multiple gaps opened by a single planet (2017, background): “…as those seen in the protoplanetary disks around HL Tau, TW Hya, HD 163296, HD 169142, AA Tau (e.g., ALMA Partnership et al. 2015; Andrews et al. 2016; Isella et al. 2016; Fedele et al. 2017; Loomis et al. 2017) can now regularly be unveiled by the extremely high resolution available with ALMA.”
A Kinematical Detection of Two Embedded Jupiter-mass Planets in HD 163296 (2018, methodology): “Similar perturbations observed in molecular line emission have been used as additional constraints on the gas surface density profile (Isella et al. 2016; Fedele et al. 2017; Teague et al. 2017).”
Direct mapping of the temperature and velocity gradients in discs Imaging the vertical CO snow line around IM Lupi (2017, background): “At these high spatial resolutions, discs very often display structures, such as dust rings and gaps (ALMA Partnership et al. 2015; Isella et al. 2016; Fedele et al. 2017; van der Plas et al. 2017).”
The Disk Substructures at High Angular Resolution Project (DSHARP). II. Characteristics of Annular Substructures (2018, background): “Colloquially, the “bright” and “dark” features are often referred to as “rings” and “gaps,” respectively (e.g., ALMA Partnership et al. 2015; Isella et al. 2016; Fedele et al. 2017).”
Multiple Disk Gaps and Rings Generated by a Single Super-Earth (2017, unknown): “Gaps (in, e.g., HD 169142; Quanz et al. 2013; Momose et al. 2015; Fedele et al. 2017).”
Gaps and Rings in an ALMA Survey of Disks in the Taurus Star-forming Region (2018, background): “Indeed, CO cavities and gaps have been reported in a few bright disks (e.g., Isella et al. 2016; Fedele et al. 2017; Boehler et al. 2018), lending some evidence for planet–disk interaction.”
The Disk Substructures at High Angular Resolution Project (DSHARP). VI. Dust Trapping in Thin-ringed Protoplanetary Disks (2018, background): “…multi-ringed disk observation of HL Tau (ALMA Partnership et al. 2015) a number of such multi-ringed disks have been detected (Andrews et al. 2016; Isella et al. 2016; Cieza et al. 2017; Fedele et al. 2017, 2018; Dipierro et al. 2018; van Terwisga et al. 2018; Clarke et al. 2018; Long et al. 2018).”