Aerodynamical sticking of dust aggregates - art. no. 046301

Citation
G. Wurm et al., Aerodynamical sticking of dust aggregates - art. no. 046301, PHYS REV E, 6404(4), 2001, pp. 6301
Citations number
16
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW E
ISSN journal
1063651X → ACNP
Volume
6404
Issue
4
Year of publication
2001
Part
2
Database
ISI
SICI code
1063-651X(200110)6404:4<6301:ASODA->2.0.ZU;2-D
Abstract
We present results of collision experiments of a dense beam of aggregated 1 .2 mum SiO2 particles entrained in a gas flow with metal targets of differe nt widths. Depending on the target width (d=25.4, 50.8, and 127 mum) and th e ambient gas pressure (p=0.5-2.0 mbar), the growth of a dust pile on the t arget begins at a threshold impact speed (v(imp)=6-12.5 m/s). These thresho ld velocities for sticking exceed the limit for total disruption of aggrega tes by more than a factor of 5-10 for the given parameters. We found that a significant number of fragments (single particles) from the collisions had a very low coefficient of restitution c(r) at least down to c(r)<0.05 that is much lower than the value c(r)>0.5 that one. of the single solid micron -sized particles would have while impinging a rigid target. Due to the drag of the gas flow these slow fragments are forced back to the target a secon d time resulting in sticking that eventually leads to the formation of the dust pile in spite of the high impact velocities. Together, the fragmentati on, the low coefficients of restitution of a significant number of fragment s, and the gas flow provide an efficient growth mechanism for bodies that w ould otherwise lose mass. We consider this an important mechanism for the f ormation of planetesimals in the solar nebula.