First detection of H2S in a protoplanetary disk

Context. Studying molecular species in protoplanetary disks is very useful to characterize the properties of these objects, which are the site of planet formation. Aims. We attempt to constrain the chemistry of S-bearing molecules in the cold parts of circumstellar disk of GG Tau A. Methods. We searched for H2S, CS, SO, and SO2 in the dense disk around GG Tau A with the NOrthem Extended Millimeter Array (NOEMA) interferometer. We analyzed our data using the radiative transfer code DiskFit and the three-phase chemical model Nautilus. Results. We detected H2S emission from the dense and cold ring orbiting around GG Tau A. This is the first detection of H2S in a protoplanetary disk. We also detected HCO+, H13CO+, and DCO+ in the disk. Upper limits for other molecules, CCS, SO2, SO, HC3N, and c-C3H2 are also obtained. The observed DCO+/HCO+ ratio is similar to those in other disks. The observed column densities, derived using our radiative transfer code DiskFit, are then compared with those from our chemical code Nautilus. The column densities are in reasonable agreement for DCO+, CS, CCS, and SO2. For H2S and SO, our predicted vertical integrated column densities are more than a factor of 10 higher than the measured values. Conclusions. Our results reinforce the hypothesis that only a strong sulfur depletion may explain the low observed H2S column density in the disk. The H2S detection in GG Tau A is most likely linked to the much larger mass of this disk compared to that in other T Tauri systems.

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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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Surface waves in protoplanetary disks induced by outbursts: Concentric rings in scattered light

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833965 ◽

2018 ◽

Vol 617 ◽

pp. L7

Author(s):

A. D. Schneider ◽

C. P. Dullemond ◽

B. Bitsch

Keyword(s):

Radiative Transfer ◽

Surface Waves ◽

Vertical Structure ◽

Near Infrared ◽

Scattered Light ◽

Protoplanetary Disks ◽

Protoplanetary Disk ◽

Diffusion Method ◽

Disk Structure ◽

Infrared Wavelengths

Context. Vertically hydrostatic protoplanetary disk models are based on the assumption that the main heating source, stellar irradiation, does not vary much with time. However, it is known that accreting young stars are variable sources of radiation. This is particularly evident for outbursting sources such as EX Lupi and FU Orionis stars. Aims. We investigate how such outbursts affect the vertical structure of the outer regions of the protoplanetary disk, in particular their appearance in scattered light at optical and near-infrared wavelengths. Methods. We employ the 3D FARGOCA radiation-hydrodynamics code, in polar coordinates, to compute the time-dependent behavior of the axisymmetric disk structure. The temperature is computed self-consistently and time-dependently from the irradiation flux using a two-stage radiative transfer method: first the direct illumination is computed; then the diffuse radiation is treated with the flux-limited diffusion method. The outbursting inner disk region is not included explicitly. Instead, its luminosity is added to the stellar luminosity and is thus included in the irradiation of the outer disk regions. For time snapshots of interest we insert the density structure into the RADMC-3D radiative transfer code and compute the appearance of the disk at optical/near-infrared wavelengths, where we observe stellar light that is scattered off the surface of the disk. Results. We find that, depending on the amplitude of the outbursts, the vertical structure of the disk can become highly dynamic, featuring circular surface waves of considerable amplitude. These “hills” and “valleys” on the disk’s surface show up in the scattered light images as bright and dark concentric rings. Initially these rings are small and act as standing waves, but they subsequently lead to outward propagating waves, like the waves produced by a stone thrown into a pond. These waves continue long after the actual outburst has died out. Conclusions. Single, periodic, or quasiperiodic outbursts of the innermost regions of protoplanetary disks will necessarily lead to wavy structures on the surface of these disks at all radii. We propose that some of the multi-ringed structures seen in optical/infrared images of several protoplanetary disks may have their origin in outbursts that occurred decades or centuries ago. However, the multiple rings seen at (sub-)millimeter wavelengths in HL Tau and several other disks are not expected to be related to such waves.

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Radiative transfer modeling of three T Tauri stars: selecting candidates for studying circumstellar disk evolution

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/13/7/008 ◽

2013 ◽

Vol 13 (7) ◽

pp. 841-848 ◽

Cited By ~ 1

Author(s):

Yao Liu ◽

Hong-Chi Wang ◽

Sebastian Wolf ◽

David Madlener

Keyword(s):

Radiative Transfer ◽

T Tauri Stars ◽

Circumstellar Disk ◽

T Tauri ◽

Disk Evolution ◽

Radiative Transfer Modeling

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Upper limits on CH3OH in the HD 163296 protoplanetary disk

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834353 ◽

2019 ◽

Vol 623 ◽

pp. A124 ◽

Cited By ~ 12

Author(s):

M. T. Carney ◽

M. R. Hogerheijde ◽

V. V. Guzmán ◽

C. Walsh ◽

K. I. Öberg ◽

...

Keyword(s):

Gas Phase ◽

Column Density ◽

Matched Filter ◽

Image Plane ◽

Protoplanetary Disk ◽

Chemical Complexity ◽

Disk Structure ◽

T Tauri ◽

Upper Limits ◽

Integrated Intensity

Context. Methanol (CH3OH) is at the root of organic ice chemistry in protoplanetary disks. Its connection to prebiotic chemistry and its role in the chemical environment of the disk midplane make it an important target for disk chemistry studies. However, its weak emission has made detections difficult. To date, gas-phase CH3OH is detected in only one Class II disk, TW Hya. Aims. We aim to constrain the methanol content of the HD 163296 protoplanetary disk. Methods. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to search for a total of four CH3OH emission lines in bands six and seven toward the disk around the young Herbig Ae star HD 163296. The disk-averaged column density of methanol and its related species formaldehyde (H2CO) were estimated assuming optically thin emission in local thermodynamic equilibrium. We compared these results to the gas-phase column densities of the TW Hya disk. Results. No targeted methanol lines were detected with Keplerian masking in the image plane nor with matched filter analysis in the uv plane individually nor after line stacking. The 3σ disk-integrated intensity upper limits are <51 mJy km s−1 for the band six lines and <26 mJy km s−1 for the band seven lines. The band seven lines provide the strictest 3σ upper limit on disk-averaged column density with Navg < 5.0 × 1011 cm−2. The methanol-to-formaldehyde ratio is CH3OH∕H2CO<0.24 in the HD 163296 disk compared to a ratio of 1.27 in the TW Hya disk. Conclusions. The HD 163296 protoplanetary disk is less abundant in methanol with respect to formaldehyde compared to the disk around TW Hya. Differences in the stellar irradiation in this Herbig Ae disk as compared to that of a disk around a T Tauri star likely influence the gaseous methanol and formaldehyde content. Possible reasons for the lower HD 163296 methanol-to-formaldehyde ratio include: a higher than expected gas-phase formation of H2CO in the HD 163296 disk, uncertainties in the grain surface formation efficiency of CH3OH and H2CO, and differences in the disk structure and/or CH3OH and H2CO desorption processes that drive the release of the molecules from ice mantles back into the gas phase. These results provide observational evidence that the gas-phase chemical complexity found in disks may be strongly influenced by the spectral type of the host star.

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Protoplanetary disks of T Tauri binary systems in the Orion nebula cluster

Astronomy and Astrophysics ◽

10.1051/0004-6361/201118314 ◽

2012 ◽

Vol 540 ◽

pp. A46 ◽

Cited By ~ 20

Author(s):

S. Daemgen ◽

S. Correia ◽

M. G. Petr-Gotzens

Keyword(s):

Binary Systems ◽

Protoplanetary Disks ◽

Orion Nebula ◽

T Tauri

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The Nobeyama Millimeter Array Survey for Protoplanetary Disks Around Protostar Candidates and T Tauri Stars in Taurus

Planetary Systems: Formation, Evolution, and Detection ◽

10.1007/978-94-011-1154-6_26 ◽

1994 ◽

pp. 239-250

Author(s):

Nagayoshi Ohashi ◽

Ryohei Kawabe ◽

Masato Ishiguro ◽

Masahiko Hayashi

Keyword(s):

Protoplanetary Disks ◽

T Tauri Stars ◽

T Tauri

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3D dust radiative transfer simulations in the inhomogeneous interstellar medium

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002785 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 490-490

Author(s):

E. Vidal Perez ◽

M. Baes

Keyword(s):

Temperature Distribution ◽

Radiative Transfer ◽

Interstellar Medium ◽

Dust Temperature ◽

T Tauri ◽

Dust Distribution ◽

Initial Results

AbstractThe study of dusty discs is an important topic in astrophysics, as they seem to be abundant around different objects and are related to different phenomena. In this poster we present 3D radiative transfer simulations of T Tauri type discs with an inhomogeneous dust distribution to investigate the effect of a clumpy medium on the dust temperature distribution. Our initial results indicate that the structure of the dust temperature distribution is rather insensitive to the structure of the ISM, but nevertheless we find a clear and systematic dependence on the parameters describing the structure of the clumpiness of the dust medium.

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