Low-velocity collisions of chondrules: How a thin dust cover helps enhance the sticking probability

¹ Institute for Materials Simulation, Department of Materials Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Dr.-Mack-Str. 77, 90762 Fürth, Germany
² Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany
³ Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
e-mail: urbassek@rhrk.uni-kl.de

Received: 29 November 2016
Accepted: 4 February 2017

Abstract

Aims. The collision of two chondrules covered by a dust shell is investigated using a granular-mechanics algorithm.

Methods. We focus on the specific case of chondrules of radius 25 μm covered by dust of 0.76 μm radius; the dust shells have thicknesses of up to 5 μm and filling factors between 0.08 and 0.21.

Results. We demonstrate that the bouncing velocity of the two chondrules increases by two orders of magnitude if a dust shell covers the chondrules. The shells become partly destroyed during the collision process, both by sputtering (monomer ejection) and by agglomeration to dust aggregates. Thicker and denser dust shells are more efficient in accommodating the collision energy than thin and porous shells.