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Brownian motion growth: self-similar. Dullemond & Dominik 2005. Sedimentation-driven growth („rainshower“). One-particle model. Equator. Sedimentation-driven growth („rainshower“). One-particle model. Equator. Sedimentation-driven growth („rainshower“). One-particle model. Equator.

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## Brownian motion growth: self-similar

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**Brownian motion growth: self-similar**Dullemond & Dominik 2005**Sedimentation-driven growth („rainshower“)**One-particle model Equator**Sedimentation-driven growth („rainshower“)**One-particle model Equator**Sedimentation-driven growth („rainshower“)**One-particle model Equator**Sedimentation-driven growth („rainshower“)**One-particle model Equator Warning: Not to scale! ;-)**Sedimentation-driven growth („rainshower“)**Equation of settling of the big dust grain: Equation of growth by sweep-up as the big grain falls: Relation between m(t) and a(t): Distribution of the small dust:**Sedimentation-driven growth („rainshower“)**Dullemond & Dominik (2005)**“Rainshower” in a disk**Dullemond & Dominik (2005)**Parallel with meteorology**Rain falling from a cumulus congestus cloud**Now with convection**Dullemond & Dominik (2005)**Parallel with meteorology**Cumulonimbus cloud, most probably with severe hail**Parallel with meteorology**Layered structure of giant hail stone**Main problem: high velocities**30 m/s = 100 km/h !! Particle size [meter]**Dust coagulation+fragmentation model**10-2 10-4 Σdust [g/cm2] 10-6 10-8 10-2 100 10-4 Grain size [cm] Birnstiel, Dullemond & Ormel 2010**Dust coagulation+fragmentation model**10-2 10-4 Σdust [g/cm2] 10-6 10-8 10-2 100 10-4 Grain size [cm] Birnstiel, Dullemond & Ormel 2010**Meter-size barrier**Rapid radial drift Aggregation Fragmentation Sweep-up growth 1m 1km 1mm 1m Meter-size barrier Growth from ‘dust’ to planetary building blocks Brownian motion Differential settling Turbulence**Bouncing barrier**Charge barrier Meter-size barrier Rapid radial drift Aggregation Fragmentation Sweep-up growth 1m 1km 1mm 1m More barriers... Growth from ‘dust’ to planetary building blocks Brownian motion Differential settling Turbulence Zsom et al. 2010, Güttler et al. 2010 Okuzumi 2009**Meter-size barrier**Rapid radial drift Aggregation Fragmentation Sweep-up growth 1m 1km 1mm 1m The “Lucky One” idea Let’s focus on the fragmentation barrier Growth from ‘dust’ to planetary building blocks Brownian motion Differential settling Turbulence**The “Lucky One” idea**Low sticking efficiency Particle abundance Windmark et al. 2012 Howtocreatetheseseeds? Perhapsvelocitydistributions: Garaud et al. 2013; Windmark et al. 2012**All the different collision outcomes...**Güttler et al. 2010**Fluffy grains, compaction, bouncing...**Zsom et al. 2010

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