X-ray photoevaporation’s limited success in the formation of planetesimals by the streaming instability

Ercolano, Barbara; Jennings, Jeff; Rosotti, Giovanni; Birnstiel, T.

doi:10.1093/mnras/stx2294

Cited by 33 publications

(19 citation statements)

References 58 publications

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“…Because the streaming instability is sensitive to the solids-togas mass ratio it could possibly be promoted by internal photoevaporation of the disc by the host star (see Carrera et al 2017;Ercolano et al 2017). In the present case of very low mass stars, internal photoevaporation is however likely to be subordinate to the effect of the environment and we do not consider this further here.…”

Section: Introductionmentioning

confidence: 92%

Where can a Trappist-1 planetary system be produced?

Haworth

Facchini

Clarke

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We study the evolution of protoplanetary discs that would have been precursors of a Trappist-1 like system under the action of accretion and external photoevaporation in different radiation environments. Dust grains swiftly grow above the critical size below which they are entrained in the photoevaporative wind, so although gas is continually depleted, dust is resilient to photoevaporation after only a short time. This means that the ratio of the mass in solids (dust plus planetary) to the mass in gas rises steadily over time. Dust is still stripped early on, and the initial disc mass required to produce the observed 4 M ⊕ of Trappist-1 planets is high. For example, assuming a Fatuzzo & Adams (2008) distribution of UV fields, typical initial disc masses have to be > 30 per cent the stellar (which are still Toomre Q stable) for the majority of similar mass M dwarfs to be viable hosts of the Trappist-1 planets. Even in the case of the lowest UV environments observed, there is a strong loss of dust due to photoevaporation at early times from the weakly bound outer regions of the disc. This minimum level of dust loss is a factor two higher than that which would be lost by accretion onto the star during 10 Myr of evolution. Consequently even in these least irradiated environments, discs that are viable Trappist-1 precursors need to be initially massive (> 10 per cent of the stellar mass).

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Section: Introductionmentioning

confidence: 92%

Where can a Trappist-1 planetary system be produced?

Haworth

Facchini

Clarke

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…For reference, in planetesimal formation models similar to ours, Carrera et al (2017) used α v = 10 −2 and α t = 10 −4 , while Ercolano et al (2017) used α v = 7 · 10 −4 and α t = 7 · 10 −6 .…”

Section: α V and α T Valuesmentioning

confidence: 99%

“…For reasons of convenience, most models of dust evolution and planetesimal formation in protoplanetary disks are computed against the backdrop of a simple stationary-state model for the gaseous disk (see e.g., Weidenschilling 1980;Stepinski & Valageas 1996, 1997Brauer et al 2008;Okuzumi et al 2012;Drażkowska et al 2016;Carrera et al 2017;Ercolano et al 2017). At the start of the simulation the dust is assumed to be all in the form of micron-size monomers, and as time goes by, the monomers stick to each other and form ever larger dust aggregates.…”

Section: Introductionmentioning

confidence: 99%

Planetesimal formation during protoplanetary disk buildup

Drążkowska

Dullemond

2018

A&A

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Context. Models of dust coagulation and subsequent planetesimal formation are usually computed on the backdrop of an already fully formed protoplanetary disk model. At the same time, observational studies suggest that planetesimal formation should start early, possibly even before the protoplanetary disk is fully formed. Aims. In this paper we investigate under which conditions planetesimals already form during the disk buildup stage, in which gas and dust fall onto the disk from its parent molecular cloud. Methods. We couple our earlier planetesimal formation model at the water snow line to a simple model of disk formation and evolution.Results. We find that under most conditions planetesimals only form after the buildup stage, when the disk becomes less massive and less hot. However, there are parameters for which planetesimals already form during the disk buildup. This occurs when the viscosity driving the disk evolution is intermediate (α v ∼ 10 −3 − 10 −2 ) while the turbulent mixing of the dust is reduced compared to that (α t 10 −4 ), and with the assumption that the water vapor is vertically well-mixed with the gas. Such a α t α v scenario could be expected for layered accretion, where the gas flow is mostly driven by the active surface layers, while the midplane layers, where most of the dust resides, are quiescent. Conclusions. In the standard picture where protoplanetary disk accretion is driven by global turbulence, we find that no planetesimals form during the disk buildup stage. Planetesimal formation during the buildup stage is only possible in scenarios in which pebbles reside in a quiescent midplane while the gas and water vapor are diffused at a higher rate.

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“…Consequently, the SI is now the de facto mechanism for planetesimal formation and is frequently applied to assess planet formation in complex disk models (Drażkowska & Dullemond 2014;Drążkowska et al 2016;Armitage et al 2016;Carrera et al 2017;Ercolano et al 2017). However, the numerical experiments that yield the criteria for the SI are often idealized, which may not fully account for physical conditions expected in real PPDs.…”

Section: Introductionmentioning

confidence: 99%

How Efficient Is the Streaming Instability in Viscous Protoplanetary Disks?

Chen

Lin

2020

ApJ

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The streaming instability is a popular candidate for planetesimal formation by concentrating dust particles to trigger gravitational collapse. However, its robustness against physical conditions expected in protoplanetary disks is unclear. In particular, particle stirring by turbulence may impede the instability. To quantify this effect, we develop the linear theory of the streaming instability with external turbulence modelled by gas viscosity and particle diffusion. We find the streaming instability is sensitive to turbulence, with growth rates becoming negligible for alpha-viscosity parameters α St 1.5 , where St is the particle Stokes number. We explore the effect of non-linear drag laws, which may be applicable to porous dust particles, and find growth rates are modestly reduced. We also find that gas compressibility increase growth rates by reducing the effect of diffusion. We then apply linear theory to global models of viscous protoplanetary disks. For minimum-mass Solar nebula disk models, we find the streaming instability only grows within disk lifetimes beyond ∼ 10s of AU, even for cm-sized particles and weak turbulence (α ∼ 10 −4 ). Our results suggest it is rather difficult to trigger the streaming instability in non-laminar protoplanetary disks, especially for small particles.

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X-ray photoevaporation’s limited success in the formation of planetesimals by the streaming instability

Cited by 33 publications

References 58 publications

Where can a Trappist-1 planetary system be produced?

Where can a Trappist-1 planetary system be produced?

Planetesimal formation during protoplanetary disk buildup

How Efficient Is the Streaming Instability in Viscous Protoplanetary Disks?

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