Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals

Gail, H. P.; Trieloff, M.

doi:10.1051/0004-6361/201730480

Cited by 55 publications

(68 citation statements)

References 84 publications

(168 reference statements)

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“…6 , we also indicate the temperatures where organic compounds are vaporized. We take the range between 325 and 425 K for the vaporization of 90% of the carbon by pyrolysis and sublimation ( 54 ). Pyrolysis and sublimation of organics convert these molecules to very volatile carbon-bearing molecules such as CH 4 , CO 2 , and CO.…”

Section: Resultsmentioning

confidence: 99%

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A pebble accretion model for the formation of the terrestrial planets in the Solar System

et al. 2021

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Pebbles of millimeter sizes are abundant in protoplanetary discs around young stars. Chondrules inside primitive meteorites—formed by melting of dust aggregate pebbles or in impacts between planetesimals—have similar sizes. The role of pebble accretion for terrestrial planet formation is nevertheless unclear. Here, we present a model where inward-drifting pebbles feed the growth of terrestrial planets. The masses and orbits of Venus, Earth, Theia (which later collided with Earth to form the Moon), and Mars are all consistent with pebble accretion onto protoplanets that formed around Mars’ orbit and migrated to their final positions while growing. The isotopic compositions of Earth and Mars are matched qualitatively by accretion of two generations of pebbles, carrying distinct isotopic signatures. Last, we show that the water and carbon budget of Earth can be delivered by pebbles from the early generation before the gas envelope became hot enough to vaporize volatiles.

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Section: Resultsmentioning

confidence: 99%

“…Only approximately 10% of the carbon provided by the pebbles will therefore make it below the region where organics are vaporized. The remaining pure carbon dust burns at 1100 K ( 54 ). This temperature is reached approximately 10,000 km above the surface of our Earth analog.…”

Section: Resultsmentioning

confidence: 99%

A pebble accretion model for the formation of the terrestrial planets in the Solar System

et al. 2021

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“…Thus, we proposed a scenario in which sticky OMGs form the seeds of planetesimals and then grow into larger, less carbon-rich planetesimals through the accretion of carbon-poor (ordinary and enstatite) chondrules ( Figure 6). These carbon-poor chondrules could also form from OMG aggregates because most carbonaceous materials contained in the precursor aggregates can be destroyed during flash heating events (Gail & Trieloff 2017). The proposed scenario for terrestrial planet formation is still highly speculative and further assessments are needed in future work.…”

Section: Resultsmentioning

confidence: 99%

Rocky Planetesimal Formation Aided by Organics

Homma

Okuzumi

Nakamoto

et al. 2019

ApJ

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The poor stickiness of silicate dust grains is a major obstacle to the formation of rocky planetesimals. In this study, we examine the possibility that silicate grains with an organic mantle, which we call Organic-Mantled Grains (OMGs), form planetesimals through direct coagulation. Organic mantles are commonly found in interplanetary dust particles, and laboratory experiments show that they are softer than silicates, in particular in warm environments. This, combined with the theory of particle adhesion, implies that OMGs are stickier than bare silicate grains. Because organic mantles can survive up to 400 K, silicate grains inside the water snow line in protoplanetary disks can in principle hold such mantles. We construct a simple grain adhesion model to estimate the threshold collision velocity below which aggregates of OMGs can grow. The model shows that aggregates of 0.1 µm-sized OMGs can overcome the fragmentation barrier in protoplanetary disks if the mantles are as thick as those in interplanetary dust particles and if the temperature is above ∼ 200 K. We use this adhesion model to simulate the global evolution of OMG aggregates in the inner part of a protoplanetary disk, demonstrating that OMG aggregates can indeed grow into planetesimals under favorable conditions. Because organic matter is unstable at excessively high temperatures, rocky planetesimal formation by the direct sticking of OMGs is expected to occur in a disk annulus corresponding to the temperature range ∼ 200-400 K. The organic-rich planetesimals may grow into carbon-poor rocky planetesimals by accreting a large amount of carbon-poor chondrules.

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“…It is unlikely that other C-destruction mechanisms can change this outcome. Adding oxidation of carbon by OH in the midplane does not increase the carbon depletion sufficiently (Gail & Trieloff 2017). For high accretion rates, the midplane region can be heated to roughly 1500 K out to 2 au (Min et al 2011).…”

Section: Resultsmentioning

confidence: 99%

Radial and vertical dust transport inhibit refractory carbon depletion in protoplanetary disks

Klarmann

Ormel

Dominik

2018

A&A

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Context. The Earth is strongly depleted in carbon compared to the dust in the ISM, implying efficient removal of refractory carbon before parent body formation. It has been argued that grains get rid of their carbon through oxidation and photolysis in the exposed upper disk layers. Aims. We assess the efficacy of these C-removal mechanisms accounting for the vertical and radial transport of grains. Methods. We obtain the carbon and carbon free mass budget of solids by solving two 1D advection-diffusion equations, accounting for the dust grain size distribution and radial transport. The carbon removal acts on the fraction of the grains that are in the exposed layer and requires efficient vertical transport. Results. In models without radial transport, oxidation and photolysis can destroy most of the refractory carbon in terrestrial planet formation region. But it only reaches the observed depletion levels for extreme parameter combinations and requires that parent body formation was delayed by 1 Myr. Adding radial transport of solids prevents the depletion entirely, leaving refractory carbon equally distributed throughout the disk. Conclusions. It is unlikely that the observed carbon depletion can ultimately be attributed to mechanisms operating on small grains in the disk surface layers. Other mechanisms need to be studied, for example flash heating events or FU Ori outbursts in order to remove carbon quickly and deeply. However, a sustained drift barrier or strongly reduced radial grain mobility are necessary to prevent replenishment of carbon from the outer disk.

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Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals

Cited by 55 publications

References 84 publications

A pebble accretion model for the formation of the terrestrial planets in the Solar System

A pebble accretion model for the formation of the terrestrial planets in the Solar System

Rocky Planetesimal Formation Aided by Organics

Radial and vertical dust transport inhibit refractory carbon depletion in protoplanetary disks

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