Initial sizes of planetesimals and accretion of the asteroids

Weidenschilling, S. J.

doi:10.1016/j.icarus.2011.05.024

Cited by 157 publications

(226 citation statements)

References 48 publications

Supporting

Mentioning

206

Contrasting

Unclassified

Order By: Relevance

“…On the other hand, Weidenschilling (2011) showed that the present size distribution observed in the asteroid belt can be also reproduced starting from planetesimals with a radius of ∼0.1 km. Kenyon & Bromley (2012) concluded that the size distribution of the transneptunian objects can be reproduced starting from a massive disk composed of relative small planetesimals (r p 10 km).…”

Section: Simultaneous Formation Of Two Embryosmentioning

confidence: 53%

Planetesimal fragmentation and giant planet formation

Guilera

Elía

Brunini

et al. 2014

A&A

View full text Add to dashboard Cite

Context. In the standard scenario of planet formation, terrestrial planets and the cores of the giant planets are formed by accretion of planetesimals. As planetary embryos grow, the planetesimal velocity dispersion increases because of gravitational excitations produced by embryos. The increasing relative velocities of the planetesimal cause them to fragment through mutual collisions. Aims. We study the role of planetesimal fragmentation on giant planet formation. We analyze how planetesimal fragmentation modifies the growth of giant planet cores for a wide range of planetesimal sizes and disk masses. Methods. We incorporated a model of planetesimal fragmentation into our model of in situ giant planet formation. We calculated the evolution of the solid surface density (planetesimals plus fragments) taking into account the accretion by the planet, migration, and fragmentation. Results. Incorporating planetesimal fragmentation significantly modifies the process of planetary formation. If most of the mass loss in planetesimal collisions is distributed in the smaller fragments, planetesimal fragmentation inhibits the growth of the embryo for initial planetesimals of radii smaller than 10 km. Only for initial planetesimals with a radius of 100 km, and disks larger than 0.06 M , embryos achieve masses larger than the mass of Earth. However, even for these large planetesimals and massive disks, planetesimal fragmentation induces the quick formation of massive cores only if most of the mass loss in planetesimal collisions is distributed in the larger fragments. Conclusions. Planetesimal fragmentation seems to play an important role in giant planet formation. The way in which the mass loss in planetesimal collisions is distributed leads to different results, inhibiting or favoring the formation of massive cores.

show abstract

Section: Simultaneous Formation Of Two Embryosmentioning

confidence: 53%

Planetesimal fragmentation and giant planet formation

Guilera

Elía

Brunini

et al. 2014

A&A

View full text Add to dashboard Cite

show abstract

“…On the other hand, a recent study of Windmark et al (2012) shows that direct growth of planetesimals via dust collisions can lead to the growth of 0.1 km planetesimals. In addition, initially small planetesimals show better matches to the observed size distribution of objects in the asteroid belt and among the trans-Neptunian objects (TNOs): Weidenschilling (2011) showed that the size distribution currently observed in the asteroid belt in the range of 10 to 100 km can be better explained by an initial population of 0.1 km planetesimals. Kenyon & Bromley (2012) concluded, by combining observations of the hot and cold populations of TNOs with time constraints on their formation process, that TNOs form from a massive disc mainly composed of 1 km planetesimals.…”

Section: Discussionmentioning

confidence: 82%

Planet formation models: the interplay with the planetesimal disc

Fortier

Alibert

Carron

et al. 2012

A&A

124

196

View full text Add to dashboard Cite

Context. According to the sequential accretion model (or core-nucleated accretion model), giant planet formation is based first on the formation of a solid core which, when massive enough, can gravitationally bind gas from the nebula to form the envelope. The most critical part of the model is the formation time of the core: to trigger the accretion of gas, the core has to grow up to several Earth masses before the gas component of the protoplanetary disc dissipates. Aims. We calculate planetary formation models including a detailed description of the dynamics of the planetesimal disc, taking into account both gas drag and excitation of forming planets. Methods. We computed the formation of planets, considering the oligarchic regime for the growth of the solid core. Embryos growing in the disc stir their neighbour planetesimals, exciting their relative velocities, which makes accretion more difficult. Here we introduce a more realistic treatment for the evolution of planetesimals' relative velocities, which directly impact on the formation timescale. For this, we computed the excitation state of planetesimals, as a result of stirring by forming planets, and gas-solid interactions. Results. We find that the formation of giant planets is favoured by the accretion of small planetesimals, as their random velocities are more easily damped by the gas drag of the nebula. Moreover, the capture radius of a protoplanet with a (tiny) envelope is also larger for small planetesimals. However, planets migrate as a result of disc-planet angular momentum exchange, with important consequences for their survival: due to the slow growth of a protoplanet in the oligarchic regime, rapid inward type I migration has important implications on intermediate-mass planets that have not yet started their runaway accretion phase of gas. Most of these planets are lost in the central star. Surviving planets have masses either below 10 M ⊕ or above several Jupiter masses. Conclusions. To form giant planets before the dissipation of the disc, small planetesimals (∼0.1 km) have to be the major contributors of the solid accretion process. However, the combination of oligarchic growth and fast inward migration leads to the absence of intermediate-mass planets. Other processes must therefore be at work to explain the population of extrasolar planets that are presently known.

show abstract

“…The region of the proto-planetary disk from which the planets formed originally contained something like 10 ∼14 objects with radii perhaps as small as ∼100 m (Weidenschilling 2011) or as large as 1000 km (Johansen & Klahr 2011) depending on the planetesimal formation model. These objects grew into planets via a process that includes both complex collisional (both accumulation and fragmentation) and dynamical evolution.…”

Section: Introductionmentioning

confidence: 99%

A Lagrangian Integrator for Planetary Accretion and Dynamics (Lipad)

Levison

Duncan

Thommes

2012

The Astronomical Journal

View full text Add to dashboard Cite

We present the first particle-based Lagrangian code that can follow the collisional/accretional/dynamical evolution of a large number of kilometer-sized planetesimals through the entire growth process of becoming planets. We refer to it as the Lagrangian Integrator for Planetary Accretion and Dynamics or LIPAD. LIPAD is built on top of SyMBA, which is a symplectic N-body integrator. In order to handle the very large number of planetesimals required by planet formation simulations, we introduce the concept of a tracer particle. Each tracer is intended to represent a large number of disk particles on roughly the same orbit and size as one another and is characterized by three numbers: the physical radius, the bulk density, and the total mass of the disk particles represented by the tracer. We developed statistical algorithms that follow the velocity and size evolution of the tracers due to close gravitational encounters and physical collisions with one another. The tracers mainly dynamically interact with the larger objects (planetary embryos) in the normal N-body way. LIPAD's greatest strength is that it can accurately model the wholesale redistribution of planetesimals due to gravitational interaction with the embryos, which has recently been shown to significantly affect the growth rate of planetary embryos. We verify the code via a comprehensive set of tests that compare our results with those of Eulerian and/or direct N-body codes.

show abstract

Initial sizes of planetesimals and accretion of the asteroids

Cited by 157 publications

References 48 publications

Planetesimal fragmentation and giant planet formation

Planetesimal fragmentation and giant planet formation

Planet formation models: the interplay with the planetesimal disc

A Lagrangian Integrator for Planetary Accretion and Dynamics (Lipad)

Contact Info

Product

Resources

About