Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line

Ida, Shigeru; Guillot, T.

doi:10.1051/0004-6361/201629680

Cited by 106 publications

(106 citation statements)

References 46 publications

(74 reference statements)

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“…In addition, the oxygen-to-hydrogen ratios in the atmospheres of Uranus and Neptune are not well-determined, although despite the large uncertainties, the existing measurements do indicate high oxygen-to-hydrogen ratios in their atmospheres, as inferred from the observed CO abundance, ranging between a few and a few hundred times the proto-solar ratio (Luszcz-Cook & dePater, 2013). Finally, we cannot exclude that formation models yield an ice to rock ratio in the protosolar disk that differs from that in the Sun (e.g., Ida & Guillot, 2016). After all, Pluto, which is located even farther out in the solar system, contains about 70% rocks (e.g., McKinnon et al, 2017).…”

Section: Are Uranus and Neptune Really "Icy" Planets?mentioning

confidence: 98%

Uranus and Neptune: Origin, Evolution and Internal Structure

2020

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There are still many open questions regarding the nature of Uranus and Neptune, the outermost planets in the Solar System. In this review we summarize the current-knowledge about Uranus and Neptune with a focus on their composition and internal structure, formation including potential subsequent giant impacts, and thermal evolution. We present key open questions and discuss the uncertainty in the internal structures of the planets due to the possibility of non-adiabatic and inhomogeneous interiors. We also provide the reasoning for improved observational constraints on their fundamental physical parameters such as their gravitational and magnetic fields, rotation rates, and deep atmospheric composition and temperature. Only this way will we be able to improve our understating of these planetary objects, and the many similar-sized objects orbiting other stars.

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Section: Are Uranus and Neptune Really "Icy" Planets?mentioning

confidence: 98%

Uranus and Neptune: Origin, Evolution and Internal Structure

2020

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“…On the other hand, another recent work by Ida & Guillot (2016) suggested different scenario of planetesimal formation, namely pile-up of dry dust grains released by the icy pebbles inside of the snow line. They find that for a sufficiently high flux of pebbles, the dust-to-gas ratio increases to a point when direct gravitational instability is possible.…”

Section: Comparison To Published Workmentioning

confidence: 99%

Planetesimal formation starts at the snow line

Drążkowska

Alibert

2017

A&A

275

266

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Context. Planetesimal formation stage represents a major gap in our understanding of the planet formation process. The late-stage planet accretion models typically make arbitrary assumptions about planetesimals and pebbles distribution while the dust evolution models predict that planetesimal formation is only possible at some orbital distances. Aims. We want to test the importance of water snow line for triggering formation of the first planetesimals during the gas-rich phase of protoplanetary disk, when cores of giant planets have to form. Methods. We connect prescriptions for gas disk evolution, dust growth and fragmentation, water ice evaporation and recondensation, as well as transport of both solids and water vapor, and planetesimal formation via streaming instability into a single, one-dimensional model for protoplanetary disk evolution. Results. We find that processes taking place around the snow line facilitate planetesimal formation in two ways. First, due to the change of sticking properties between wet and dry aggregates, there is a "traffic jam" inside of the snow line that slows down the fall of solids onto the star. Second, ice evaporation and outward diffusion of water followed by its recondensation increases the abundance of icy pebbles that trigger planetesimal formation via streaming instability just outside of the snow line. Conclusions. Planetesimal formation is hindered by growth barriers and radial drift and thus requires particular conditions to take place. Snow line is a favorable location where planetesimal formation is possible for a wide range of conditions, but still not in every protoplanetary disk model. This process is particularly promoted in large, cool disks with low intrinsic turbulence and increased initial dust-to-gas ratio.

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“…However, the high dust-to-ice remains puzzling because condensation of ice outside the snow line would suggest values around unity (Lodders 2003). Ida & Guillot (2016) proposed that planetesimals with a high dust-to-ice ratio could form just inside the snow line, where sublimation of icy aggregates drifting in from the outer disk releases small silicate dust grains that accumulate and form planetesimals by gravitational instability. However, it is not clear how to incorporate highly volatile species into the nucleus in this scenario, which makes it less favourable for comet formation.…”

Section: Disk Structurementioning

confidence: 99%

Local growth of dust- and ice-mixed aggregates as cometary building blocks in the solar nebula

Lorek

Lacerda

Blum

2018

A&A

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Context. Comet formation by gravitational instability requires aggregates that trigger the streaming instability and cluster in pebble-clouds. These aggregates form as mixtures of dust and ice from (sub-)micrometre-sized dust and ice grains via coagulation in the solar nebula. Aim. We investigate the growth of aggregates from (sub-)micrometre-sized dust and ice monomer grains. We are interested in the properties of these aggregates: whether they might trigger the streaming instability, how they compare to pebbles found on comets, and what the implications are for comet formation in collapsing pebble-clouds. Methods. We used Monte Carlo simulations to study the growth of aggregates through coagulation locally in the comet-forming region at 30 au. We used a collision model that can accommodate sticking, bouncing, fragmentation, and porosity of dust- and ice-mixed aggregates. We compared our results to measurements of pebbles on comet 67P/Churyumov-Gerasimenko. Results. We find that aggregate growth becomes limited by radial drift towards the Sun for 1 μm sized monomers and by bouncing collisions for 0.1 μm sized monomers before the aggregates reach a Stokes number that would trigger the streaming instability (Stmin). We argue that in a bouncing-dominated system, aggregates can reach Stmin through compression in bouncing collisions if compression is faster than radial drift. In the comet-forming region (~30 au), aggregates with Stmin have volume-filling factors of ~10−2 and radii of a few millimetres. These sizes are comparable to the sizes of pebbles found on comet 67P/Churyumov-Gerasimenko. The porosity of the aggregates formed in the solar nebula would imply that comets formed in pebble-clouds with masses equivalent to planetesimals of the order of 100 km in diameter.

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Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line

Cited by 106 publications

References 46 publications

Uranus and Neptune: Origin, Evolution and Internal Structure

Uranus and Neptune: Origin, Evolution and Internal Structure

Planetesimal formation starts at the snow line

Local growth of dust- and ice-mixed aggregates as cometary building blocks in the solar nebula

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