EDP Sciences
Free access
Issue
A&A
Volume 480, Number 3, March IV 2008
Page(s) 859 - 877
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20077759
Published online 20 November 2007


A&A 480, 859-877 (2008)
DOI: 10.1051/0004-6361:20077759

Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks

F. Brauer, C. P. Dullemond, and Th. Henning

Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
    e-mail: brauer@mpia.de

(Received 30 April 2007 / Accepted 11 November 2007)

Abstract
The growth of solid particles towards meter sizes in protoplanetary disks has to circumvent at least two hurdles, namely the rapid loss of material due to radial drift and particle fragmentation due to destructive collisions. In this paper, we present the results of numerical simulations with more and more realistic physics involved. Step by step, we include various effects, such as particle growth, radial/vertical particle motion and dust particle fragmentation in our simulations. We demonstrate that the initial dust-to-gas ratio is essential for the particles to overcome the radial drift barrier. If this value is increased by a factor of 2 compared with the canonical value for the interstellar medium, km-sized bodies can form in the inner disk (<2 AU) within 104 yrs. However, we find that solid particles get destroyed through collisional fragmentation. Only with the unrealistically high-threshold velocities needed for fragmentation to occur (>30 m/s), particles are able to grow to larger sizes in disks with low $\alpha$ values. We also find that less than 5% of the small dust grains remain in the disk after 1 Myr due to radial drift, no matter whether fragmentation is included in the simulations or not. In this paper, we also present considerable improvements to existing algorithms for dust-particle coagulation, which speed up the coagulation scheme by a factor of ~104.


Key words: accretion, accretion disks -- circumstellar matter -- stars: formation -- stars: pre-main-sequence -- infrared: stars -- planetary systems: protoplanetary disks



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