The Streaming Instability, Photophoresis and Planetesimal Formation at the Inner Edge of Protoplanetary Disks

• Applicants: Professor Dr. H. Hubertus Klahr; Professor Dr. Gerhard Wurm
• Subject Area: Astrophysics and Astronomy
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 323230386

• Final Report Year: 2021

Final Report Abstract

The dynamics of dense particle clouds is crucial for the evolution of dust and pebbles toward planetesimals. In laboratory experiments we could show for the first time that particles in clouds behave collectively above a certain critical number density, i.e. showing a sedimentation velocity strongly depending on the closeness of other particles and the overall density in the Stokes regime. A particle clump, simulated by a highly porous aggregate - important in their own respect - can experience order of magnitude higher drag forces than the cross section would suggest, depending on the porosity and size of the constituents and overall size. We give quantitative empirical equations to calculate effective gas-grain coupling times and gas drag.

Publications

• Laboratory Experiments on the Motion of Dense Dust Clouds in Protoplanetary Disks, Astrophysical Journal Letters, 886:L36 1-5, 2019
  N. Schneider and G. Wurm
  
• Streaming Instabilities in Laboratory Experiments, Astrophysical Journal, 872:3 1-12, 2019
  N. Schneider, G. Wurm, J. Teiser, H. Klahr, and V. Carpenter
  
• Destruction of Eccentric Planetesimals by Ram Pressure and Erosion, Astronomy and Astrophysics, 644:A20 1-5, 2020
  T. Demirci, N. Schneider, J. Teiser, and G. Wurm
  
• Planetesimals in Rarefied Gas: Wind Erosion in Slip Flow, Monthly Notices of the Royal Astronomical Society, 493:5456-5463, 2020
  T. Demirci, N. Schneider, T. Steinpilz, T. Bogdan, J. Teiser, and G.Wurm
  
• Turbulence Sets the Length Scale for Planetesimal Formation: Local 2D Simulations of Streaming Instability and Planetesimal Formation. The Astrophysical Journal 901, 2020
  H. Klahr and A. Schreiber
  
• Cosmic Radiation does not Prevent Collisional Charging in (Pre)-Planetary Atmospheres, Icarus, 355:114127 1-7, 2021
  F. Jungmann, T Bila, L. Kleinert, A. Mölleken, R. Möller, L. Schmidt, N. Schneider, J. Teiser, D. Utzat, V. Volkenborn, and G. Wurm
  
• Drag Forces on Porous Aggregates in Protoplanetary Disks, Astronomy and Astrophysics, 655:A50 1-7, 2021
  N. Schneider and G. Wurm
  
• Experimental Study of Clusters in Dense Granular Gas and Implications for the Particle Stopping Time in Protoplanetary Disks, Icarus, 360:114307 1-8, 2021
  N. Schneider, G. Musiolik, J. E. Kollmer, T. Steinpilz, M. Kruss, F. Jungmann, T. Demirci, J. Teiser, and G. Wurm