Gas and Dust Dynamics in Starlight-heated Protoplanetary Disks

Flock, Mario; Turner, Neal; Nelson, Richard P.; Lyra, Wladimir; Manger, Natascha; Klahr, Hubert

doi:10.3847/1538-4357/ab9641

Cited by 95 publications

(123 citation statements)

References 83 publications

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“…This distribution of icy dust grains and molecules requires efficient vertical transport in the disk, which can be achieved by turbulent mixing (Semenov & Wiebe 2011). In addition, the dynamics of the vortex itself may play a role as both the vertical shear instability (Flock et al 2020) and meridional flows (Meheut et al 2010) in vortices increase the vertical mixing. The full scenario of the ice reservoir, mixing, and sublimation is summarized in the bottom panels of Fig.…”

Section: Discussionmentioning

confidence: 99%

A major asymmetric ice trap in a planet-forming disk

Marel

Booth

Leemker

et al. 2021

A&A

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Context. The chemistry of planet-forming disks sets the exoplanet atmosphere composition and the prebiotic molecular content. Dust traps are of particular importance as pebble growth and transport are crucial for setting the chemistry where giant planets form. Aims. The asymmetric Oph IRS 48 dust trap located at 60 au radius provides a unique laboratory for studying chemistry in pebbleconcentrated environments in warm Herbig disks with gas-to-dust ratios as low as 0.01. Methods. We use deep ALMA Band 7 line observations to search the IRS 48 disk for H 2 CO and CH 3 OH line emission, the first steps of complex organic chemistry. Results. We report the detection of seven H 2 CO and six CH 3 OH lines with energy levels between 17 and 260 K. The line emission shows a crescent morphology, similar to the dust continuum, suggesting that the icy pebbles play an important role in the delivery of these molecules. Rotational diagrams and line ratios indicate that both molecules originate from warm molecular regions in the disk with temperatures >100 K and column densities ∼ 10 14 cm −2 or a fractional abundance of ∼ 10 −8 and with H 2 CO/CH 3 OH∼0.2, indicative of ice chemistry. Based on arguments from a physical-chemical model with low gas-to-dust ratios, we propose a scenario where the dust trap provides a huge icy grain reservoir in the disk midplane, or an 'ice trap', which can result in high gas-phase abundances of warm complex organic molecules through efficient vertical mixing. Conclusions. This is the first time that complex organic molecules have been clearly linked to the presence of a dust trap. These results demonstrate the importance of including dust evolution and vertical transport in chemical disk models as icy dust concentrations provide important reservoirs for complex organic chemistry in disks.

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Section: Discussionmentioning

confidence: 99%

A major asymmetric ice trap in a planet-forming disk

Marel

Booth

Leemker

et al. 2021

A&A

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“…The possibility of the presence of vortices formed by VSI was first found by Richard et al (2016) in the r−φ plane. These vortices can be long-lived locally around 500 orbits (Manger & Klahr 2018) with an H R = 0.1 and with an azimuthal and radial extension of about 40 and 4 au (Flock et al 2020), respectively. In our case the vortices appear in the r−Z plane, mostly inside the region between two large-scale upward and downward motions.…”

Section: Small-scale Vorticesmentioning

confidence: 99%

Hydrodynamical simulations of protoplanetary disks including irradiation of stellar photons

Flores-Rivera

Flock

Nakatani

2020

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Context. In recent years hydrodynamical (HD) models have become important to describe the gas kinematics in protoplanetary disks, especially in combination with models of photoevaporation and/or magnetically driven winds. Our aim is to investigate how vertical shear instability (VSI) could influence the thermally driven winds on the surface of protoplanetary disks. Aims. In this first part of the project, we focus on diagnosing the conditions of the VSI at the highest numerical resolution ever recorded, and suggest at what resolution per scale height we obtain convergence. At the same time, we want to investigate the vertical extent of VSI activity. Finally, we determine the regions where extreme UV (EUV), far-UV (FUV), and X-ray photons are dominant in the disk. Methods. We perform global HD simulations using the PLUTO code. We adopt a global isothermal accretion disk setup, 2.5D (2 dimensions, 3 components) which covers a radial domain from 0.5 to 5.0 and an approximately full meridional extension. Our simulation runs cover a resolution from 12 to 203 cells per scale height. Results. We determine 50 cells per scale height to be the lower limit to resolve the VSI. For higher resolutions, ≥50 cells per scale height, we observe the convergence for the saturation level of the kinetic energy. We are also able to identify the growth of the “body” modes, with higher growth rate for higher resolution. Full energy saturation and a turbulent steady state is reached after 70 local orbits. We determine the location of the EUV heated region defined by Σr = 1019 cm−2 to be at HR ~ 9.7 and the FUV–X-ray heated boundary layer defined by Σr = 1022 cm−2 to be at HR ~ 6.2, making it necessary to introduce a hot atmosphere. For the first time we report the presence of small-scale vortices in the r − Z plane between the characteristic layers of large-scale vertical velocity motions. Such vortices could lead to dust concentration, promoting grain growth. Our results highlight the importance of combining photoevaporation processes in the future high-resolution studies of turbulence and accretion processes in disks.

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“…To verify the scale height determined using this latter technique, we follow another approach outlined in Flock et al (2020) and plot the averaged vertical dust density profile (see Fig. 6).…”

Section: Vertical Dust Scale Height and Effective αmentioning

confidence: 99%

Streaming instability in a global patch simulation of protoplanetary disks

Flock

Mignone

2021

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Aims. In recent years, sub-millimeter (mm) observations of protoplanetary disks have revealed an incredible diversity of substructures in the dust emission. An important result was the finding that dust grains of mm size are embedded in very thin dusty disks. This implies that the dust mass fraction in the midplane becomes comparable to that of the gas, increasing the importance of the interaction between the two components there. Methods. We use numerical 2.5D simulations to study the interaction between gas and dust in fully globally stratified disks. To this end, we employ the recently developed dust grain module of the PLUTO code. Our model focuses on a typical T Tauri disk model, simulating a short patch of the disk at 10 au which includes grains of a constant Stokes number of St = 0.01 and St = 0.1, corresponding to grains with sizes of 0.9 cm and 0.9 mm, respectively, for the given disk model. Results. By injecting a constant pebble flux at the outer domain, the system reaches a quasi-steady state of turbulence and dust concentrations driven by the streaming instability. For our given setup, and using resolutions up to 2500 cells per scale height, we resolve the streaming instability that leads to local dust clumping and concentrations. Our results show dust density values of around 10–100 times the gas density with a steady-state pebble flux of between 3.5 × 10−4 and 2.5 × 10−3 MEarth yr−1 for the models with St = 0.01 and St = 0.1. Conclusions. Grain size and pebble flux for model St = 0.01 compare well with dust evolution models of the first million years of disk evolution. For those grains, the scatter opacity dominates the extinction coefficient at mm wavelengths. These types of global dust and gas simulations are a promising tool for studies of the gas and dust evolution at pressure bumps in protoplanetary disks.

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Gas and Dust Dynamics in Starlight-heated Protoplanetary Disks

Cited by 95 publications

References 83 publications

A major asymmetric ice trap in a planet-forming disk

A major asymmetric ice trap in a planet-forming disk

Hydrodynamical simulations of protoplanetary disks including irradiation of stellar photons

Streaming instability in a global patch simulation of protoplanetary disks

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