Effect of nucleation on icy pebble growth in protoplanetary discs

Ros, Katrin; Johansen, Anders; Riipinen, Ilona; Schlesinger, Daniel

doi:10.1051/0004-6361/201834331

Cited by 48 publications

(43 citation statements)

References 79 publications

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“…& Wurm 2019;Ros et al 2019;Vericel & Gonzalez 2020;Ziampras et al 2020). In future studies, we plan to improve our model by introducing H 2 O, CO, and CO 2 snow lines and adopting dust fragmentation velocity (u frag ) depending on the position of dust particle relative to the snow line.…”

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confidence: 99%

Gravitoviscous protoplanetary disks with a dust component

Elbakyan

Johansen²,

Lambrechts³

et al. 2020

A&A

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Aims. We study the dynamics and growth of dust particles in circumstellar disks of different masses that are prone to gravitational instability during the critical first Myr of their evolution. Methods. We solved the hydrodynamics equations for a self-gravitating and viscous circumstellar disk in a thin-disk limit using the FEOSAD numerical hydrodynamics code. The dust component is made up of two different components: micron-sized dust and grown dust of evolving size. For the dust component, we considered the dust coagulation, fragmentation, momentum exchange with the gas, and dust self-gravity. Results. We found that the micron-sized dust particles grow rapidly in the circumstellar disk, reaching a few cm in size in the inner 100 au of the disk during less than 100 kyr after the disk formation, provided that fragmentation velocity is 30 ms−1. Due to the accretion of micron dust particles from the surrounding envelope, which serves as a micron dust reservoir, the approximately cm-sized dust particles continue to be present in the disk for more than 900 kyr after the disk formation and maintain a dust-to-gas ratio close to 0.01. We show that a strong correlation exists between the gas and pebble fluxes in the disk. We find that radial surface density distribution of pebbles in the disk shows power-law distribution with an index similar to that of the Minimum-mass solar nebula regardless the disk mass. We also show that the gas surface density in our models agrees well with measurements of dust in protoplanetary disks of AS 209, HD 163296, and DoAr 25 systems. Conclusions. Pebbles are formed during the very early stages of protoplanetary disk evolution. They play a crucial role in the planet formation process. Our disc simulations reveal the early onset (<105 yr) of an inwards-drifting flux of pebble-sized particles that makes up approximately between one hundredth and one tenth of the gas mass flux, which appears consistent with mm-observations of discs. Such a pebble flux would allow for the formation of planetesimals by streaming instability and the early growth of embryos by pebble accretion. We conclude that unlike the more common studies of isolated steady-state protoplanetary disks, more sophisticated global numerical simulations of circumstellar disk formation and evolution, including the pebble formation from the micron dust particles, are needed for performing realistic planet formation studies.

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confidence: 99%

Gravitoviscous protoplanetary disks with a dust component

Elbakyan

Johansen²,

Lambrechts³

et al. 2020

A&A

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“…Solid particles in the protoplanetary disc experience a drag force due to the turbulent motion of gas in the disc. The resultant turbulent diffusion of the particles can be modeled as a damped random walk, which we implement using the algorithm from Ros et al (2019). They calculate the turbulent diffusion coefficient (D) by applying a force acceleration ( f ) to the particles on a time-scale τ for , and damping the turbulent velocity on the correlation time-scale τ cor .…”

Section: Turbulent Velocitymentioning

confidence: 99%

“…The forcing time-step τ for is set to equal the time-step of the simulation, and the correlation time is the approximate time-scale over which a particle maintains a coherent direction, calculated as the inverse of the Keplerian angular velocity (τ cor = Ω −1 ). As an addition to the algorithm from Ros et al (2019), the falling of D with Stokes number is implemented here following eq. 37 in Youdin & Lithwick (2007).…”

Section: Turbulent Velocitymentioning

confidence: 99%

“…The code we use for simulations is called PLANETESYS, and is a modified version of the Pencil Code (Brandenburg & Dobler 2002), designed for highly parallel calculations of the evolution of gas and dust particles in protoplanetary discs. The code is developed under the ERC Consolidator Grant "PLANETESYS" (PI: Anders Johansen) and this paper together with the recent paper by Ros & Johansen (2019) represent the first publications using this tool. The evolution of the surface density is solved using a first order finite difference scheme with an adaptive time-step.…”

Section: Numerical Setupmentioning

confidence: 99%

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Pebble drift and planetesimal formation in protoplanetary discs with embedded planets

Eriksson

Johansen

Liu

2020

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Nearly-axisymmetric gaps and rings are commonly observed in protoplanetary discs. The leading theory regarding the origin of these patterns is that they are due to dust trapping at the edges of gas gaps induced by the gravitational torques from embedded planets. If the concentration of solids at the gap edges becomes high enough, it could potentially result in planetesimal formation by the streaming instability. We test this hypothesis by performing global 1-D simulations of dust evolution and planetesimal formation in a protoplanetary disc that is perturbed by multiple planets. We explore different combinations of particle sizes, disc parameters, and planetary masses, and find that planetesimals form in all these cases. We also compare the spatial distribution of pebbles from our simulations with protoplanetary disc observations. Planets larger than one pebble isolation mass catch drifting pebbles efficiently at the edge of their gas gaps, and depending on the efficiency of planetesimal formation at the gap edges, the protoplanetary disc transforms within a few 100,000 years to either a transition disc with a large inner hole devoid of dust or to a disc with narrow bright rings. For simulations with planetary masses lower than the pebble isolation mass, the outcome is a disc with a series of weak ring patterns but no strong depletion between the rings. Lowering the pebble size artificially to 100 micrometer-sized "silt", we find that regions between planets get depleted of their pebble mass on a longer time-scale of up to 0.5 million years. These simulations also produce fewer planetesimals than in the nominal model with millimeter-sized particles and always have at least two rings of pebbles still visible after 1 Myr.

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“…Phase transformation is the process involving transitioning from one state of matter to another, such as liquid to solid or gas to liquid or gas to solid transformations. These transformations are very common in nature, including phenomena such as crystallization and amyloid aggregation (liquid to solid transformation), rain precipitation (gas to liquid transformation) and planet formation (gas to solid transformation) (Karthika et al, 2016;Ros et al, 2019). That is why both the thermodynamics and kinetics of phase transformation have been widely studied.…”

Section: Amyloid Nucleation Mechanismsmentioning

confidence: 99%

Disentangling the Amyloid Pathways: A Mechanistic Approach to Etiology

et al. 2020

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Amyloids are fibrillar protein aggregates associated with diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), type II diabetes and Creutzfeldt-Jakob disease. The process of amyloid polymerization involves three pathological protein transformations; from natively folded conformation to the cross-β conformation, from biophysically soluble to insoluble, and from biologically functional to non-functional. While amyloids share a similar cross-β conformation, the biophysical transformation can either take place spontaneously via a homogeneous nucleation mechanism (HON) or catalytically on an exogenous surface via a heterogeneous nucleation mechanism (HEN). Here, we postulate that the different nucleation pathways can serve as a mechanistic basis for an etiological classification of amyloidopathies, where hereditary forms generally follow the HON pathway, while sporadic forms follow seed-induced (prions) or surface-induced (including microbially induced) HEN pathways. Critically, the conformational and biophysical amyloid transformation results in loss-of-function (LOF) of the original natively folded and soluble protein. This LOF can, at least initially, be the mechanism of amyloid toxicity even before amyloid accumulation reaches toxic levels. By highlighting the important role of non-protein species in amyloid formation and LOF mechanisms of toxicity, we propose a generalized mechanistic framework that could help better understand the diverse etiology of amyloid diseases and offer new opportunities for therapeutic interventions, including replacement therapies.

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Effect of nucleation on icy pebble growth in protoplanetary discs

Cited by 48 publications

References 79 publications

Gravitoviscous protoplanetary disks with a dust component

Gravitoviscous protoplanetary disks with a dust component

Pebble drift and planetesimal formation in protoplanetary discs with embedded planets

Disentangling the Amyloid Pathways: A Mechanistic Approach to Etiology

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