Physical properties of particle agglomerates with respects to the planet formation process

• Applicants: Professor Dr. Jürgen Blum; Professor Dr. Wilhelm Kley (†)
• Subject Area: Astrophysics and Astronomy
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 196513527

• Final Report Year: 2017

Final Report Abstract

The project has dealt with two important aspects of dust with respect to the planet formation process. In a first part we have performed molecular dynamics simulations to of dust agglomerates, that consisted of a large number of individual monomers. After careful calibration we used this direct method to calculate continuum properties of dust agglomerates such as tensile and shear strength that are difficult to access experimentally. By considering collisions between agglomerates we could show that bouncing between particles occurs only for large filling factor and low velocities, and that the fragmentation barrier can be shifted to 10m/s, and beyond for non-equal collision partners. Both effects tend to relax the bouncing as well as fragmentation barrier. In the second part we studied the interaction of the dust with the ambient gas in turbulent disks that are driven by the VSI. Here, we find first a strong bunching of the particles in the turbulent eddies (rolls), and secondly relative velocities of about 10m/s that would just allow for further particles growth. Wit respect to the stochastic nature of the flow, we could show that the turbulence is strongly anisotropic. Embedded planets experience a faster inward migration than classical type I. We have extended the study of embedded planets by including the accretion properties of dust particles.

Publications

• Compression behavior of porous dust agglomerates, 2012, A&A 541, A59
  Seizinger, A.; Speith, R. & Kley, W.
  (See online at https://doi.org/10.1051/0004-6361/201218855)
• The Physics of Protoplanetesimal Dust Agglomerates. VII. The Low-velocity Collision Behavior of Large Dust Agglomerates, 2012, ApJ 758, id.35
  Schräpler, R.; Blum, J.; Seizinger, A. & Kley, W.
  (See online at https://doi.org/10.1088/0004-637X/758/1/35)
• 2013, The properties of dust agglomerates, Dissertation, University of Tübingen
  Seizinger, A.
  
• Bouncing behavior of microscopic dust aggregates, 2013, A&A 551, A65
  Seizinger, A. & Kley, W.
  (See online at https://doi.org/10.1051/0004-6361/201220946)
• Erosion of dust aggregates, 2013, A&A 560, A45
  Seizinger, A.; Krijt, S. & Kley, W.
  (See online at https://doi.org/10.1051/0004-6361/201322773)
• Tensile and shear strength of porous dust agglomerates, 2013, A&A 559, A19
  Seizinger, A.; Speith, R. & Kley, W.
  (See online at https://doi.org/10.1051/0004-6361/201322046)
• Bridging the Gap Between Hydrocodes, 2015, LPI Contribution No. 1861, p.1082
  Martellato, E.; Schäfer, C.; Wandel, O.; Cremonese, G. & Kley, W.
  
• Particle dynamics in discs with turbulence generated by the vertical shear instability, 2016, A&A 594, A57
  Stoll, M.H.R. & Kley, W.
  (See online at https://doi.org/10.1051/0004-6361/201527716)
• 2017, Dynamics of Dust and Planets in turbulent Accretion Disks, Dissertation, University of Tübingen
  Stoll, M.
  (See online at https://dx.doi.org/10.15496/publikation-17926)
• Anisotropic hydrodynamic turbulence in accretion disks, 2017, A&A 599, L6
  Stoll, M.H.R.; Kley, W. & Picogna, G.
  (See online at https://doi.org/10.1051/0004-6361/201630226)
• Planet-disc interaction in laminar and turbulent discs, 2017, A&A 604, A28
  Stoll, M.H.R.; Picogna, G. & Kley, W.
  (See online at https://doi.org/10.1051/0004-6361/201730668)