How to form planetesimals from mm-sized chondrules and chondrule aggregates

Carrera, Daniel; Johansen, Anders; Davies, Melvyn B.

doi:10.1051/0004-6361/201425120

Cited by 266 publications

(366 citation statements)

References 51 publications

(77 reference statements)

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“…As the flux of pebbles from the outer disc continues, pebbles accumulate in the pressure bump and the pebble-to-gas ratio increases. However, an increased pebble-to-gas ratio will trigger the streaming instability (Bai & Stone 2010;Carrera et al 2015), transforming the pebbles into planetesimals. For the streaming instability to occur, a vertically integrated pebble-to-gas ratio of a few percent is needed.…”

Section: Mass Loading In the Pressure Bumpmentioning

confidence: 99%

Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants

Bitsch

Morbidelli

Johansen

et al. 2018

A&A

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248

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The growth of a planetary core by pebble accretion stops at the so-called pebble isolation mass, when the core generates a pressure bump that traps drifting pebbles outside its orbit. The value of the pebble isolation mass is crucial in determining the final planet mass. If the isolation mass is very low, gas accretion is protracted and the planet remains at a few Earth masses with a mainly solid composition. For higher values of the pebble isolation mass, the planet might be able to accrete gas from the protoplanetary disc and grow into a gas giant. Previous works have determined a scaling of the pebble isolation mass with cube of the disc aspect ratio. Here, we expand on previous measurements and explore the dependency of the pebble isolation mass on all relevant parameters of the protoplanetary disc. We use 3D hydrodynamical simulations to measure the pebble isolation mass and derive a simple scaling law that captures the dependence on the local disc structure and the turbulent viscosity parameter α. We find that small pebbles, coupled to the gas, with Stokes number τ f < 0.005 can drift through the partial gap at pebble isolation mass. However, as the planetary mass increases, particles must be decreasingly smaller to penetrate the pressure bump. Turbulent diffusion of particles, however, can lead to an increase of the pebble isolation mass by a factor of two, depending on the strength of the background viscosity and on the pebble size. We finally explore the implications of the new scaling law of the pebble isolation mass on the formation of planetary systems by numerically integrating the growth and migration pathways of planets in evolving protoplanetary discs. Compared to models neglecting the dependence of the pebble isolation mass on the α-viscosity, our models including this effect result in higher core masses for giant planets. These higher core masses are more similar to the core masses of the giant planets in the solar system.

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Section: Mass Loading In the Pressure Bumpmentioning

confidence: 99%

Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants

Bitsch

Morbidelli

Johansen

et al. 2018

A&A

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248

284

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“…These spiral arms are regions of high particle and gas density, which may be conducive to giant planet formation (e.g., dust traps as in van der Marel et al 2013). Indeed, planetesimal formation through the streaming instability (Youdin & Goodman 2005;Johansen et al 2007) as well as subsequent core growth through pebble accretion ) exhibit a strong dependence on the local density of solids (Carrera et al 2015). Recent high contrast Very Large Telescope/SPHERE imaging of the protoplanetary disk around HD 100453, which has an M dwarf companion located at a distance of 120 au, revealed the presence of spiral structures (Wagner et al 2015).…”

Section: Are Multi-stellar Systems More Favorable For Gas Giantmentioning

confidence: 99%

FRIENDS OF HOT JUPITERS. IV. STELLAR COMPANIONS BEYOND 50 au MIGHT FACILITATE GIANT PLANET FORMATION, BUT MOST ARE UNLIKELY TO CAUSE KOZAI–LIDOV MIGRATION

Ngo

Knutson

Hinkley

et al. 2016

ApJ

154

169

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Stellar companions can influence the formation and evolution of planetary systems, but there are currently few observational constraints on the properties of planet-hosting binary star systems. We search for stellar companions around 77 transiting hot Jupiter systems to explore the statistical properties of this population of companions as compared to field stars of similar spectral type. After correcting for survey incompleteness, we find that  47% 7% of hot Jupiter systems have stellar companions with semimajor axes between 50 and 2000 au. This is 2.9 times larger than the field star companion fraction in this separation range, with a significance of s 4.4 . In the 1-50 au range, only -+ 3.9 % 2.0 4.5 of hot Jupiters host stellar companions, compared to the field star value of  16.4% 0.7%, which is a s 2.7 difference. We find that the distribution of mass ratios for stellar companions to hot Jupiter systems peaks at small values and therefore differs from that of field star binaries which tend to be uniformly distributed across all mass ratios. We conclude that either wide separation stellar binaries are more favorable sites for gas giant planet formation at all separations, or that the presence of stellar companions preferentially causes the inward migration of gas giant planets that formed farther out in the disk via dynamical processes such as Kozai-Lidov oscillations. We determine that less than 20% of hot Jupiters have stellar companions capable of inducing KozaiLidov oscillations assuming initial semimajor axes between 1 and 5 au, implying that the enhanced companion occurrence is likely correlated with environments where gas giants can form efficiently.

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“…Photoevaporation may be key to forming planetesimals by the streaming instability, because pebble-sized particles can only concentrate in regions of elevated metallicity compared to the nominal 1% value of the solar photosphere (Johansen et al 2009;Bai & Stone 2010;Carrera et al 2015). In a complementary work, Drazkowska et al (2016) also modelled the evolution of dust in an evolving disk.…”

Section: Introductionmentioning

confidence: 99%

Planetesimal Formation by the Streaming Instability in a Photoevaporating Disk

Carrera¹,

Gorti

Johansen³

et al. 2017

ApJ

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157

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Recent years have seen growing interest in the streaming instability as a candidate mechanism to produce planetesimals. However, these investigations have been limited to small-scale simulations. We now present the results of a global protoplanetary disk evolution model that incorporates planetesimal formation by the streaming instability, along with viscous accretion, photoevaporation by EUV, FUV, and X-ray photons, dust evolution, the water ice line, and stratified turbulence. Our simulations produce massive (60-130 M ⊕ ) planetesimal belts beyond 100 au and up to ∼ 20M ⊕ of planetesimals in the middle regions (3-100 au). Our most comprehensive model forms 8 M ⊕ of planetesimals inside 3 au, where they can give rise to terrestrial planets. The planetesimal mass formed in the inner disk depends critically on the timing of the formation of an inner cavity in the disk by high-energy photons. Our results show that the combination of photoevaporation and the streaming instability are efficient at converting the solid component of protoplanetary disks into planetesimals. Our model, however, does not form enough early planetesimals in the inner and middle regions of the disk to give rise to giant planets and super-Earths with gaseous envelopes. Additional processes such as particle pileups and mass loss driven by MHD winds may be needed to drive the formation of early planetesimal generations in the planet forming regions of protoplanetary disks.

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How to form planetesimals from mm-sized chondrules and chondrule aggregates

Cited by 266 publications

References 51 publications

Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants

Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants

FRIENDS OF HOT JUPITERS. IV. STELLAR COMPANIONS BEYOND 50 au MIGHT FACILITATE GIANT PLANET FORMATION, BUT MOST ARE UNLIKELY TO CAUSE KOZAI–LIDOV MIGRATION

Planetesimal Formation by the Streaming Instability in a Photoevaporating Disk

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