Evolution of porous dust grains in protoplanetary discs – I. Growing grains

Garcia, Anthony J. L.; Gonzalez, Jean-François

doi:10.1093/mnras/staa382

Cited by 23 publications

(20 citation statements)

References 73 publications

(121 reference statements)

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“…To close this section, it is important to mention that the results of Musiolik & Wurm (2019) have been regarded as controversial by some authors. Garcia & Gonzalez (2020) point out that the results of Musiolik & Wurm (2019) disagree with the tensile strength computed numerically by Tatsuuma et al (2019). Okuzumi & Tazaki (2019) mention that Musiolik's recent experiments are inconsistent with earlier ones performed by Gundlach & Blum (2015), which showed efficient sticking of H 2 O grains for temperatures down to 100 K. In addition, missing key aspects such as porosity (Garcia & Gonzalez 2020;Krijt et al 2016) and the lack of experiments involving mixtures of silicates and ices (Choukroun et al 2020) Fig.…”

Section: Appendix A: Dependence On the Fragmentation Velocity Of Grainsmentioning

confidence: 81%

The nature of the radius valley

Venturini

Guilera

Haldemann

et al. 2020

A&A

146

117

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The existence of a radius valley in the Kepler size distribution stands as one of the most important observational constraints to understand the origin and composition of exoplanets with radii between those of Earth and Neptune. In this work we provide insights into the existence of the radius valley, first from a pure formation point of view and then from a combined formation-evolution model. We run global planet formation simulations including the evolution of dust by coagulation, drift, and fragmentation, and the evolution of the gaseous disc by viscous accretion and photoevaporation. A planet grows from a moon-mass embryo by either silicate or icy pebble accretion, depending on its position with respect to the water ice line. We include gas accretion, type I–II migration, and photoevaporation driven mass-loss after formation. We perform an extensive parameter study evaluating a wide range of disc properties and initial locations of the embryo. We find that due to the change in dust properties at the water ice line, rocky cores form typically with ∼3 M⊕ and have a maximum mass of ∼5 M⊕, while icy cores peak at ∼10 M⊕, with masses lower than 5 M⊕ being scarce. When neglecting the gaseous envelope, the formed rocky and icy cores account naturally for the two peaks of the Kepler size distribution. The presence of massive envelopes yields planets more massive than ∼10 M⊕ with radii above 4 R⊕. While the first peak of the Kepler size distribution is undoubtedly populated by bare rocky cores, as shown extensively in the past, the second peak can host half-rock–half-water planets with thin or non-existent H-He atmospheres, as suggested by a few previous studies. Some additional mechanisms inhibiting gas accretion or promoting envelope mass-loss should operate at short orbital periods to explain the presence of ∼10–40 M⊕ planets falling in the second peak of the size distribution.

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Section: Appendix A: Dependence On the Fragmentation Velocity Of Grainsmentioning

confidence: 81%

The nature of the radius valley

Venturini

Guilera

Haldemann

et al. 2020

A&A

146

117

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“…Many studies show that porosity is important for pebble evolution and for hit-and-stick growth (Dominik & Tielens 1997;Ormel et al 2007;Garcia & Gonzalez 2020). For our experiments, we use two pebble models that have negligible porosity at the beginning of the sublimation experiment.…”

Section: Role Of Porositymentioning

confidence: 99%

The fate of icy pebbles undergoing sublimation in protoplanetary discs

Spadaccia,

Capelo,

Pommerol

et al. 2021

Preprint

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Icy pebbles may play an important role in planet formation close to the water ice line of protoplanetary discs. There, dust coagulation is more efficient and re-condensation of vapor on pebbles may enhance their growth outside the ice line. Previous theoretical studies showed that disruption of icy pebbles due to sublimation increases the growth rate of pebbles inside and outside the ice line, by freeing small silicate particles back in the dust reservoir of the disc. However, since planet accretion is dependent on the Stokes number of the accreting pebbles, the growth of planetesimals could be enhanced downstream of the ice line if pebbles are not disrupting upon sublimation. We developed two experimental models of icy pebbles using different silicate dusts, and we exposed them to low-temperature and low-pressure conditions in a vacuum chamber. Increasing the temperature inside the chamber, we studied the conditions for which pebbles are preserved through sublimation without disrupting. We find that small silicate particles (< 50 µm) and a small quantity of ice (around 15 % pebble mass) are optimal conditions for preserving pebbles through sublimation. Furthermore, pebbles with coarse dust distribution (100 − 300 µm) do not disrupt if a small percentage (10 − 20 % mass) of dust grains are smaller than 50 µm. Our findings highlight how sublimation is not necessarily causing disruption, and that pebbles seem to survive fast sublimation processes effectively.

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“…They are likely to go through a turbulent evolutionary path, colliding, coagulating, and fragmenting, as they migrate through the disk (e.g., Laibe et al 2008;Birnstiel et al 2012;Krijt et al 2016;Schoonenberg et al 2018). Some grains may never reach the inner edge if grain growth is sufficiently fast (e.g., Okuzumi et al 2012;Garcia & Gonzalez 2020). Even at the edge itself, opacity should evolve over time as grain size evolves.…”

Section: Recession Of the Disk Edgementioning

confidence: 99%

Dust Dynamics in Transitional Disks: Clumping and Disk Recession

Bi,

Fung

2022

Preprint

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The role of radiation pressure in dust migration and the opening of inner cavities in transitional disks is revisited in this paper. Dust dynamics including radiation pressure is often studied in axisymmetric models, but in this work, we show that highly non-axisymmetric features can arise from an instability at the inner disk edge. Dust grains clump into high density features there, allowing radiation to leak around them and penetrate deeper into the disk, changing the course of dust migration. Our proofof-concept, two-dimensional, vertically-averaged simulations show that the combination of radiation pressure, shadowing, and gas drag can produce a net outward migration, or recession, of the dust component of the disk. The recession speed of the inner disk edge is on the order of 10 −5 times Keplerian speed in our parameter space, which is faster than the background viscous flow, assuming a Shakura & Sunyaev viscosity α 10 −3 . This speed, if sustained over the lifetime of the disk, can result in a dust cavity as large as tens of au.

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Evolution of porous dust grains in protoplanetary discs – I. Growing grains

Cited by 23 publications

References 73 publications

The nature of the radius valley

The nature of the radius valley

The fate of icy pebbles undergoing sublimation in protoplanetary discs

Dust Dynamics in Transitional Disks: Clumping and Disk Recession

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