Observations of edge-on protoplanetary disks with ALMA

Aims. We aim to study vertical settling and radial drift of dust in protoplanetary disks from a different perspective: an edge-on view. An estimation of the amplitude of settling and drift is highly relevant to understanding planet formation. Methods. We analyze a sample of 12 HST-selected edge-on protoplanetary disks (i.e., seen with high inclinations) for which the vertical extent of the emission layers can be constrained directly. We present ALMA high angular resolution continuum images (~0.1′′) of these disks at two wavelengths, 0.89 and 2.06 mm (respectively ALMA bands 7 and 4), supplemented with archival band 6 data (1.33 mm) where available. Results. Several sources show constant brightness profiles along their major axis with a steep drop at the outer edges. Two disks have central holes with additional compact continuum emission at the location of the central star. For most sources, the millimeter continuum emission is more compact than the scattered light, both in the vertical and radial directions. Six sources are resolved along their minor axis in at least one millimetric band, providing direct information on the vertical distribution of the millimeter grains. For the second largest disk of the sample, Tau 042021, the significant difference in vertical extent between band 7 and band 4 suggests efficient size-selective vertical settling of large grains. Furthermore, the only Class I object in our sample shows evidence of flaring in the millimeter. Along the major axis, all disks are well resolved. Four of them are larger in band 7 than in band 4 in the radial direction, and three have a similar radial extent in all bands. These three disks are also the ones with the sharpest apparent edges (between 80% and 20% of the peak flux, Δr∕r ~ 0.3), and two of them are binaries. For all disks, we also derive the millimeter brightness temperature and spectral index maps. We find that all edge-on disks in our sample are likely optically thick and that the dust emission reveals low brightness temperatures in most cases (brightness temperatures ≤10 K). The integrated spectral indices are similar to those of disks at lower inclination. Conclusions. The comparison of a generic radiative transfer disk model with our data shows that at least three disks are consistent with a small millimeter dust scale height, of a few au (measured at r = 100 au). This is in contrast with the more classical value of hg ~ 10 au derived from scattered light images and from gas line measurements. These results confirm, by direct observations, that large (millimeter) grains are subject to significant vertical settling in protoplanetary disks.

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A 10-M⊙ YSO with a Keplerian disk and a nonthermal radio jet

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834366 ◽

2019 ◽

Vol 622 ◽

pp. A206 ◽

Cited By ~ 7

Author(s):

L. Moscadelli ◽

A. Sanna ◽

R. Cesaroni ◽

V. M. Rivilla ◽

C. Goddi ◽

...

Keyword(s):

Dust Emission ◽

Major Axis ◽

High Mass ◽

Continuum Emission ◽

High Angular Resolution ◽

Central Mass ◽

Disk Radius ◽

Dynamical Interaction ◽

Linear Pattern ◽

Nonthermal Radio

Context. To constrain present star formation models, we need to simultaneously establish the dynamical and physical properties of disks and jets around young stars. Aims. We previously observed the star-forming region G16.59−0.05 through interferometric observations of both thermal and maser lines, and identified a high-mass young stellar object (YSO) which is surrounded by an accretion disk and drives a nonthermal radio jet. Our goals are to establish the physical conditions of the environment hosting the high-mass YSO and to study the kinematics of the surrounding gas in detail. Methods. We performed high-angular-resolution (beam FWHM ≈ 0′′.15) 1.2-mm continuum and line observations towards G16.59−0.05 with the Atacama Large Millimeter Array (ALMA). Results. The main dust clump, with size ≈104 au, is resolved into four distinct, relatively compact (diameter ~2000 au) millimeter (mm) sources. The source harboring the high-mass YSO is the most prominent in molecular emission. By fitting the emission profiles of several unblended and optically thin transitions of CH3OCH3 and CH3OH, we derived gas temperatures inside the mm sources in the range 42–131 K, and calculated masses of 1–5 M⊙. A well-defined Local Standard of Rest (LSR) velocity (VLSR) gradient is detected in most of the high-density molecular tracers at the position of the high-mass YSO, pinpointed by compact 22-GHz free-free emission. This gradient is oriented along a direction forming a large (≈70°) angle with the radio jet, traced by elongated 13-GHz continuum emission. The butterfly-like shapes of the P–V plots and the linear pattern of the emission peaks of the molecular lines at high velocity confirm that this VLSR gradient is due to rotation of the gas in the disk surrounding the high-mass YSO. The disk radius is ≈500 au, and the VLSR distribution along the major axis of the disk is well reproduced by a Keplerian profile around a central mass of 10 ± 2 M⊙. The position of the YSO is offset by ≳0′′.1 from the axis of the radio jet and the dust emission peak. To explain this displacement we argue that the high-mass YSO could have moved from the center of the parental mm source owing to dynamical interaction with one or more companions.

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Dust-driven viscous ring-instability in protoplanetary disks

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731878 ◽

2018 ◽

Vol 609 ◽

pp. A50 ◽

Cited By ~ 24

Author(s):

C. P. Dullemond ◽

A. B. T. Penzlin

Keyword(s):

Surface Density ◽

Scattered Light ◽

Protoplanetary Disks ◽

Continuum Emission ◽

Rotational Instability ◽

Local Pressure ◽

Ionization Degree ◽

Local Maxima ◽

Gas Ionization ◽

Small Dust

Protoplanetary disks often appear as multiple concentric rings in dust continuum emission maps and scattered light images. These features are often associated with possible young planets in these disks. Many non-planetary explanations have also been suggested, including snow lines, dead zones and secular gravitational instabilities in the dust. In this paper we suggest another potential origin. The presence of copious amounts of dust tends to strongly reduce the conductivity of the gas, thereby inhibiting the magneto-rotational instability, and thus reducing the turbulence in the disk. From viscous disk theory it is known that a disk tends to increase its surface density in regions where the viscosity (i.e. turbulence) is low. Local maxima in the gas pressure tend to attract dust through radial drift, increasing the dust content even more. We have investigated mathematically if this could potentially lead to a feedback loop in which a perturbation in the dust surface density could perturb the gas surface density, leading to increased dust drift and thus amplification of the dust perturbation and, as a consequence, the gas perturbation. We find that this is indeed possible, even for moderately small dust grain sizes, which drift less efficiently, but which are more likely to affect the gas ionization degree. We speculate that this instability could be triggered by the small dust population initially, and when the local pressure maxima are strong enough, the larger dust grains get trapped and lead to the familiar ring-like shapes. We also discuss the many uncertainties and limitations of this model.

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Observational signatures of eccentric Jupiters inside gas cavities in protoplanetary discs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab1045 ◽

2021 ◽

Author(s):

Clément Baruteau ◽

Gaylor Wafflard-Fernandez ◽

Romane Le Gal ◽

Florian Debras ◽

Andrés Carmona ◽

...

Keyword(s):

Large Scale ◽

Near Infrared ◽

Scattered Light ◽

Dust Emission ◽

Three Dimensional ◽

Continuum Emission ◽

Integrated Intensity ◽

Gas Cavity ◽

Hydrodynamical Simulations ◽

Small Dust

Abstract Predicting how a young planet shapes the gas and dust emission of its parent disc is key to constraining the presence of unseen planets in protoplanetary disc observations. We investigate the case of a 2 Jupiter mass planet that becomes eccentric after migrating into a low-density gas cavity in its parent disc. Two-dimensional hydrodynamical simulations are performed and post-processed by three-dimensional radiative transfer calculations. In our disc model, the planet eccentricity reaches ∼0.25, which induces strong asymmetries in the gas density inside the cavity. These asymmetries are enhanced by photodissociation and form large-scale asymmetries in 12CO J=3→2 integrated intensity maps. They are shown to be detectable for an angular resolution and a noise level similar to those achieved in ALMA observations. Furthermore, the planet eccentricity renders the gas inside the cavity eccentric, which manifests as a narrowing, stretching and twisting of iso-velocity contours in velocity maps of 12CO J=3→2. The planet eccentricity does not, however, give rise to detectable signatures in 13CO and C18O J=3→2 inside the cavity because of low column densities. Outside the cavity, the gas maintains near-circular orbits, and the vertically extended optically thick CO emission displays a four-lobed pattern in integrated intensity maps for disc inclinations $\gtrsim$ 30○. The lack of large and small dust inside the cavity in our model further implies that synthetic images of the continuum emission in the sub-millimetre, and of polarized scattered light in the near-infrared, do not show significant differences when the planet is eccentric or still circular inside the cavity.

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First Results from ATCA at Millimetre Wavelengths

Symposium - International Astronomical Union ◽

10.1017/s0074180900241685 ◽

2004 ◽

Vol 221 ◽

pp. 275-282

Author(s):

Vincent Minier

Keyword(s):

Star Formation ◽

Angular Resolution ◽

Galactic Plane ◽

Dust Emission ◽

Protoplanetary Disks ◽

High Angular Resolution ◽

Star Forming ◽

Star Forming Regions ◽

First Results ◽

Excellent Tool

The newly upgraded Australia Telescope Compact Array (ATCA) at millimetre wavelengths is the first millimetre interferometer to be built in the Southern Hemisphere. The full array will be operational in 2004-2005 and will provide arcsec angular resolution at 3 mm and 12 mm. This will be a unique instrument to study at high angular resolution the interstellar chemistry and more generally the star formation process, especially in the bulk of the galactic plane and in the Magellanic Clouds. The upgraded ATCA will also be an excellent tool to detect dust emission from nearby protoplanetary disks. In this paper I will present the first results from the upgraded ATCA at 3 mm and 12 mm. The result review will cover the topics of massive star formation and hot molecular cores dust emission from star-forming regions and detection of protoplanetary disks.

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Shadowing and multiple rings in the protoplanetary disk of HD 139614

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936509 ◽

2020 ◽

Vol 635 ◽

pp. A121 ◽

Cited By ~ 3

Author(s):

G. A. Muro-Arena ◽

M. Benisty ◽

C. Ginski ◽

C. Dominik ◽

S. Facchini ◽

...

Keyword(s):

Radiative Transfer ◽

Scattered Light ◽

Protoplanetary Disks ◽

Position Angle ◽

Protoplanetary Disk ◽

Disk Model ◽

Outer Disk ◽

Planetary Mass ◽

Azimuthal Asymmetries ◽

Multiple Rings

Context. Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly caused by an inclined (sub-)stellar companion embedded in the disk. Aims. We aim to study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. Methods. We obtained J- and H-band observations that show strong azimuthal asymmetries in polarized scattered light with VLT/SPHERE. In the outer disk, beyond ~30 au, a broad shadow spans a range of ~240 deg in position angle, in the east. A bright ring at ~16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at ~34 and ~50 au. We created a simple four-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast. Results. We find that the shadow on the outer disk covers a range of position angles too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones – or a continuously warped region – to cast this broad shadow on the outer disk. A small misalignment of ~4° between adjacent components can reproduce most of the observed shadow features. Conclusions. Multiple misaligned disk zones, potentially mimicking a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust-depleted gap responsible for a dip in the SED.

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High angular resolution study of the super star cluster population in IRAS 17138−1017

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037755 ◽

2020 ◽

Vol 639 ◽

pp. A28

Author(s):

N. T. Lam ◽

D. Gratadour ◽

D. Rouan ◽

L. Grosset

Keyword(s):

Radiative Transfer ◽

Near Infrared ◽

Thermal Emission ◽

Scattered Light ◽

Dust Emission ◽

High Angular Resolution ◽

Evolutionary Track ◽

Imaging Data ◽

Host Galaxies ◽

Super Star Clusters

Aims. Currently, the global characteristics and evolution of super star clusters (SSCs) are not well understood, due to the large distances to their host galaxies. We aim to study the population of SSCs in IRAS 17138-1017, a luminous infrared galaxy (LIRG), in terms of age, extinction, mass, and luminosity distribution. Methods. We analyzed imaging data in the near-infrared from the GeMS/GSAOI instrument on the Gemini telescope and generated simulations with the radiative transfer code MontAGN. The extraction of SSCs from the images and their photometry in J, H, and Ks allowed us to derive color-color and color-magnitude diagrams. Comparison with a theoretical stellar evolutionary track gives a first hint into the extinction towards each SSC, as well as their ages, despite some degeneracy between those two quantities. Spectra given by our radiative transfer code MontAGN, which includes dust emission, also provide insightful predictions and comparisons. Results. We detect with a fair degree of confidence 54 SSCs of mKs between 16 mag and 21 mag with a median instrumental uncertainty of 0.05 mag. When plotted on a color–color diagram and a color–magnitude diagram, it appears that most of the sources are very much extinct with respect to an intrinsic theoretical evolutionary track. Once de-reddened, the colors point unambiguously to two distinct and very recent starburst episodes at 2.8 and 4.5 Myr. While the SSCs in the 4.5 Myr starburst are distributed along the spiral arms, the 2.8 Myr SSCs are concentrated in the central region. The luminosity and mass functions present a classical power-law behavior, although with shallower slopes than generally observed in LIRGs. Comparison with radiative transfer simulations shows that, the dust thermal emission and scattered light are negligible and could not explain the few very red SSCs that could not be de-reddened safely.

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Small-scale properties of Class 0 protostars from the CALYPSO IRAM-PdBI survey

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316007365 ◽

2015 ◽

Vol 11 (S315) ◽

pp. 114-117

Author(s):

Anaëlle Maury ◽

Philippe André ◽

Sébastien Maret ◽

Arnaud Belloche ◽

Claudio Codella ◽

...

Keyword(s):

Angular Momentum ◽

Angular Resolution ◽

Dust Emission ◽

Continuum Emission ◽

Small Scale ◽

High Angular Resolution ◽

Multiple Systems ◽

Small Scales ◽

Molecular Lines ◽

Scale Properties

AbstractBecause the formation of protostars is believed to be closely tied to the angular momentum problem of star formation, characterizing the properties of the youngest disks around Class 0 objects is crucial. However, not much is known on the structure of the youngest protostellar envelopes, on the small scales at which disks and multiple systems are observed around more evolved YSOs, due to a lack of comprehensive high angular resolution observations (probing <100 AU). In order to tackle this issue, we conducted a large observing program with the IRAM Plateau de Bure interferometer (PdBI): the CALYPSO survey, providing us with detailed maps of molecular lines and millimeter continuum emission, probing scales down to ~30–50 au towards a sample of 17 Class 0 protostars. Here we present our analysis of the CALYPSO dust continuum emission maps, constraining disk properties of the Class 0 protostars in our sample. We show that large, r > 50 au, disk structures are not observed in most Class 0 protostars from our sample, which can be described by various envelope models reproducing satisfactorily the intensity distribution of the dust emission at all scales from 50 au to 5000 au.

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THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL

The Astrophysical Journal ◽

10.1088/0004-637x/750/2/161 ◽

2012 ◽

Vol 750 (2) ◽

pp. 161 ◽

Cited By ~ 89

Author(s):

R. Dong ◽

R. Rafikov ◽

Z. Zhu ◽

L. Hartmann ◽

B. Whitney ◽

...

Keyword(s):

Scattered Light ◽

Protoplanetary Disks ◽

Disk Model

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Resolved spectral variations of the centimetre-wavelength continuum from the ρ Oph W photo-dissociation-region

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa4016 ◽

2021 ◽

Author(s):

Simon Casassus ◽

Matías Vidal ◽

Carla Arce-Tord ◽

Clive Dickinson ◽

Glenn J White ◽

...

Keyword(s):

Molecular Cloud ◽

Dust Emission ◽

Image Synthesis ◽

Microwave Emission ◽

Radio Continuum ◽

Continuum Emission ◽

Parametric Image ◽

Physical Conditions ◽

Morphological Differences ◽

Dust Grain

Abstract Cm-wavelength radio continuum emission in excess of free-free, synchrotron and Rayleigh-Jeans dust emission (excess microwave emission, EME), and often called ‘anomalous microwave emission’, is bright in molecular cloud regions exposed to UV radiation, i.e. in photo-dissociation regions (PDRs). The EME correlates with IR dust emission on degree angular scales. Resolved observations of well-studied PDRs are needed to compare the spectral variations of the cm-continuum with tracers of physical conditions and of the dust grain population. The EME is particularly bright in the regions of the ρ Ophiuchi molecular cloud (ρ Oph) that surround the earliest type star in the complex, HD 147889, where the peak signal stems from the filament known as the ρ Oph-W PDR. Here we report on ATCA observations of ρ Oph-W that resolve the width of the filament. We recover extended emission using a variant of non-parametric image synthesis performed in the sky plane. The multi-frequency 17 GHz to 39 GHz mosaics reveal spectral variations in the cm-wavelength continuum. At ∼30 arcsec resolutions, the 17-20 GHz intensities follow tightly the mid-IR, Icm∝I(8 μm), despite the breakdown of this correlation on larger scales. However, while the 33-39 GHz filament is parallel to IRAC 8 μm, it is offset by 15–20 arcsec towards the UV source. Such morphological differences in frequency reflect spectral variations, which we quantify spectroscopically as a sharp and steepening high-frequency cutoff, interpreted in terms of the spinning dust emission mechanism as a minimum grain size acutoff ∼ 6 ± 1 Å that increases deeper into the PDR.

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