High Spatial Resolution Observations of Molecular Lines toward the Protoplanetary Disk around TW Hya with ALMA

Nomura, Hideko; Tsukagoshi, Takashi; Kawabe, Ryohei; Muto, Takayuki; Kanagawa, Kazuhiro D.; Aikawa, Yuri; Akiyama, Eiji; Okuzumi, Satoshi; Ida, Shigeru; Lee, Seokho; Walsh, Catherine; Millar, T. J.

doi:10.3847/1538-4357/abfb6a

Cited by 20 publications

(21 citation statements)

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“…In C 18 O emission, Fedele et al (2017) found evidence for a cavity inside 𝑟 ≈ 50 au and used DALI to infer (Müller et al 2018;Keppler et al 2018;Wang et al 2020). (6) Gas surface density at the planet's location, as inferred from C 18 O emission (Nomura et al 2021;Zhang et al 2021;Favre et al 2019;Fedele et al 2017;Isella et al 2016;Facchini et al 2021). The quoted ranges on Σ gas in AS 209, IM Lup, HD 163296, and TW Hya accommodate the possibility that the CO:H 2 abundance ratio in these discs is lower than in the ISM (Zhang et al 2019;Calahan et al 2021;Zhang et al 2021).…”

Section: Gas Surface Density: Hd 169142mentioning

confidence: 99%

“…(7) Dust surface density at the planet's location (Huang et al 2018;Nomura et al 2021;Fedele et al 2017;Benisty et al 2021) Σ gas ≈ 0.1 − 0.2 g/cm 2 near the cavity outer edge (their figure 5, top left panel, blue curve). Midplane gas temperatures according to the same thermo-chemical model (figure 5, bottom center panel) are ∼30 − 40 K, higher than the CO freeze-out temperature of ∼20 K. CO may still be depleted for other reasons (Schwarz et al 2018) but without a model we cannot quantify the uncertainty.…”

Section: Gas Surface Density: Hd 169142mentioning

confidence: 99%

“…The inner gap may also have been detected in the mm continuum by Andrews et al (2016), albeit slightly outside the gap in scattered light (their figure 2). Nomura et al (2021) studied TW Hya in the 𝐽 = 3 − 2 transition of C 18 O. Near the inner gap they measured a wavelength-integrated line flux of 5 mJy beam −1 km s −1 (their figure 2, middle panel, orange curve).…”

Section: Gas Surface Density: Tw Hyamentioning

confidence: 99%

“…For TW Hya-G1 at 21 au we calculate Σ dust = 0.054 − 0.38 g/cm 2 using equations ( 1)-( 2) with 𝐼 𝜈 = 10 mJy beam −1 (figure 2, middle panel, purple curve of Nomura et al 2021) and 𝑇 = 60 K (section 2.3.3). For TW Hya-G2 at 85 au we estimate Σ dust = 0.0022 − 0.015 g/cm 2 using 𝐼 𝜈 ∼ 10 −1 mJy beam −1 (this is an extrapolation of the intensity profile measured by Nomura et al 2021 which does not extend beyond ∼70 au) and 𝑇 = 20 K. Our estimates of Σ dust are consistent with those plotted in figure 3 of Nomura et al (2021).…”

Section: Dust Surface Density: Tw Hyamentioning

confidence: 99%

“…Systems are listed in order of increasing host stellar mass 𝑀 ★ , except for PDS 70 which as the only transitional disc in our sample is placed at the end. For TW Hya we estimate Σ gas from the C 18 O line flux (Nomura et al 2021), while for AS 209, IM Lup, HD 169142, and HD 163296 Σ gas derives from detailed thermo-chemical modeling (Favre et al 2019;Zhang et al 2021;Fedele et al 2017;Isella et al 2016). For PDS 70, we bound Σ gas using the C 18 O 2-1 flux outside the disc cavity and the 12 CO 3-2 flux inside the cavity (Facchini et al 2021) 1, with red points added to mark Σ gas predicted from equation ( 6).…”

Section: Planetary Accretion Rates and Gap Propertiesmentioning

confidence: 99%

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Testing planet formation from the ultraviolet to the millimeter

Choksi,

Chiang

2021

Preprint

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Gaps imaged in protoplanetary discs are suspected to be opened by planets. We compute the present-day mass accretion rates 𝑀 p of seven hypothesized gap-embedded planets, plus the two confirmed planets in PDS 70, by combining disc gas surface densities Σ gas from C 18 O observations with planet masses 𝑀 p from simulations fitted to observed gaps. Assuming accretion is Bondi-like, we find in eight out of nine cases that 𝑀 p is consistent with the time-averaged value given by the current planet mass and system age, 𝑀 p /𝑡 age . As system ages are comparable to circumstellar disc lifetimes, these gap-opening planets may be undergoing their last mass doublings, reaching final masses of 𝑀 p ∼ 10 − 10 2 𝑀 ⊕ for the non-PDS 70 planets, and 𝑀 p ∼ 1 − 10 𝑀 J for the PDS 70 planets. For another fifteen gaps without C 18 O data, we predict Σ gas by assuming their planets are accreting at their time-averaged 𝑀 p . Bondi accretion rates for PDS 70b and c are orders of magnitude higher than accretion rates implied by measured U-band and H𝛼 fluxes, suggesting most of the accretion shock luminosity emerges in as yet unobserved wavebands, or that the planets are surrounded by dusty, highly extincting, quasi-spherical circumplanetary envelopes. Thermal emission from such envelopes or from circumplanetary discs, on Hill sphere scales, peaks at wavelengths in the mid-to-far-infrared, and can reproduce observed mm-wave excesses. Key words: planets and satellites: formation -planets and satellites: general -planets and satellites: fundamental parametersprotoplanetary discs -planet-disc interactions 1 The gaps simulated by Zhang et al. (2018) and similar works are opened because of the repulsive Lindblad torques exerted by planets. These planetdisk simulations neglect accretion onto the planet (cf. Rosenthal et al. 2020 and references therein).

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Section: Gas Surface Density: Hd 169142mentioning

confidence: 99%

Section: Gas Surface Density: Hd 169142mentioning

confidence: 99%

Section: Gas Surface Density: Tw Hyamentioning

confidence: 99%

Section: Dust Surface Density: Tw Hyamentioning

confidence: 99%

Section: Planetary Accretion Rates and Gap Propertiesmentioning

confidence: 99%

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Testing planet formation from the ultraviolet to the millimeter

Choksi,

Chiang

2021

Preprint

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Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk

Paneque-Carreño

Miotello

Dishoeck

et al. 2022

A&A

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Context. Cyanide (CN) emission is expected to originate in the upper layers of protoplanetary disks, tracing UV-irradiated regions. This hypothesis, however, has been observationally tested only in a handful of disks. Elias 2-27 is a young star that hosts an extended, bright, and inclined disk of dust and gas. The inclination and extreme flaring of the disk make Elias 2-27 an ideal target to study the vertical distribution of molecules, particularly CN. Aims. Our aim is to directly trace the emission of CN in the disk around Elias 2-27 and compare it to previously published CO isotopolog data of the system. The two tracers can be combined and used to constrain the physical and chemical properties of the disk. Through this analysis we can test model predictions of CN emission and compare observations of CN in other objects to the massive, highly flared, asymmetric, and likely gravitationally unstable protoplanetary disk around Elias 2-27. Methods. We analyzed CN N = 3 − 2 emission in two different transitions J = 7/2 − 5/2 and J = 5/2 − 3/2, for which we detect two hyperfine group transitions. The vertical location of CN emission was traced directly from the channel maps, following geometrical methods that had been previously used to analyze the CO emission of Elias 2-27. Simple analytical models were used to parameterize the vertical profile of each molecule and study the extent of each tracer. From the radial intensity profiles we computed radial profiles of column density and optical depth. Results. We show that the vertical location of CN and CO isotopologs in Elias 2-27 is layered and consistent with predictions from thermochemical models. A north-south asymmetry in the radial extent of the CN emission is detected, which is likely due to shadowing on the north side of the disk. Combining the information from the peak brightness temperature and vertical structure radial profiles, we find that the CN emission is mostly optically thin and constrained vertically to a thin slab at z/r ∼0.5. A column density of 10 14 cm −2 is measured in the inner disk, which for the north side decreases to 10 12 cm −2 and for the south side to 10 13 cm −2 in the outer regions. Conclusions. In Elias 2-27, CN traces a vertically elevated region above the midplane, very similar to that traced by 12 CO. The inferred CN column densities, low optical depth (τ ≤1), and location near the disk surface are consistent with thermo-chemical disk models in which CN formation is initiated by the reaction of N with UV-pumped H 2 . The observed north-south asymmetry may be caused by either ongoing infall or by a warped inner disk. This study highlights the importance of tracing the vertical location of various molecules to constrain the disk physical conditions.

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AB Aur, a Rosetta stone for studies of planet formation

Riviére-Marichalar

Fuente

Esplugues

et al. 2022

A&A

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Context. The sulfur abundance is poorly known in most environments. Yet, deriving the sulfur abundance is key to understanding the evolution of the chemistry from molecular clouds to planetary atmospheres. We present observations of H 2 S 1 10 − 1 01 at 168.763 GHz toward the Herbig Ae star AB Aur. Aims. We aim to study the abundance of sulfuretted species toward AB Aur and to constrain how different species and phases contribute to the sulfur budget. Methods. We present new NOrthern Extended Millimeter Array (NOEMA) interferometric observations of the continuum and H 2 S 1 10 − 1 01 line at 168.763 GHz toward AB Aur. We derived radial and azimuthal profiles and used them to compare the geometrical distribution of different species in the disk. Assuming local thermodynamical equilibrium (LTE), we derived column density and abundance maps for H 2 S, and we further used Nautilus to produce a more detailed model of the chemical abundances at different heights over the mid-plane at a distance of r=200 au. Results. We have resolved H 2 S emission in the AB Aur protoplanetary disk. The emission comes from a ring extending from 0.67 (∼109 au) to 1.69 (∼275 au). Assuming T=30 K, n H =10 9 cm −3 , and an ortho-to-para ratio of three, we derived a column density of (2.3±0.5)×10 13 cm −2 . Under simple assumptions, we derived an abundance of (3.1±0.8)×10 −10 with respect to H nuclei, which we compare with Nautilus models to deepen our understanding of the sulfur chemistry in protoplanetary disks. Chemical models indicate that H 2 S is an important sulfur carrier in the solid and gas phase. We also find an important transition at a height of ∼12 au, where the sulfur budget moves from being dominated by ice species to being dominated by gas species. Conclusions. We confirm that present-day models still struggle to simultaneously reproduce the observed column densities of the different sulfuretted species, and the observed abundances are still orders of magnitude away from the cosmic sulfur abundance. Studying sulfuretted species in detail in the different phases of theinterstellar medium is key to solving the issue.

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High Spatial Resolution Observations of Molecular Lines toward the Protoplanetary Disk around TW Hya with ALMA

Cited by 20 publications

References 53 publications

Testing planet formation from the ultraviolet to the millimeter

Testing planet formation from the ultraviolet to the millimeter

Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk

AB Aur, a Rosetta stone for studies of planet formation

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