Planetesimals in rarefied gas: wind erosion in slip flow. Issue 4 (3rd March 2020)

• Record Type: Journal Article
• Authors: Demirci, Tunahan; Schneider, Niclas; Steinpilz, Tobias; Bogdan, Tabea; Teiser, Jens; Wurm, Gerhard
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 493:Issue 4(2020)
• Page Start: 5456
• Page End: 5463
• Publication Date: 2020-03-03
• Subjects: planets and satellites: dynamical evolution and stability -- planets and satellites: formation -- planets and satellites: physical evolution -- planet-disc interaction -- protoplanetary discs; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa607
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: A planetesimal moves through the gas of its protoplanetary disc where it experiences a head wind. Though the ambient pressure is low, this wind can erode and ultimately destroy the planetesimal if the flow is strong enough. For the first time, we observe wind erosion in ground-based and microgravity experiments at pressures relevant in protoplanetary discs, i.e. down to $10^{-1}\, \rm mbar$ . We find that the required shear stress for erosion depends on the Knudsen number related to the grains at the surface. The critical shear stress to initiate erosion increases as particles become comparable to or larger than the mean free path of the gas molecules. This makes pebble pile planetesimals more stable at lower pressure. However, it does not save them as the experiments also show that the critical shear stress to initiate erosion is very low for sub-millimetre-sized grains.