Destruction of eccentric planetesimals by ram pressure and erosion

University of Duisburg-Essen, Faculty of Physics, Lotharstr. 1, 47057 Duisburg, Germany
e-mail: tunahan.demirci@uni-due.de

Received: 1 September 2020
Accepted: 22 October 2020

Abstract

Small, pebble-sized objects and large bodies of planetesimal size both play important roles in planet formation. They form the evolutionary steps of dust growth in their own respect. However, at later times, they are also thought to provide background populations of mass that larger bodies might feed upon. What we suggest in this work is that starting at times of viscous stirring, planetesimals on eccentric orbits could simply explode as they become supersonic in comparison to small, porous planetary bodies entering Earth’s atmosphere. We present a toy model of planetesimal motion and destruction to show the key aspects of this process. The consequences are quite severe. At all times, it is shown that only planetesimals on more or less circular orbits exist in the inner disk. After the destruction of a planetesimal, the remaining matter is continuously redistributed to the pebble reservoir of the protoplanetary disk. Since destruction typically occurs at small stellar distances due to supersonic speeds, it is expected to boost pebble accretion in the inner protoplanetary disk as one of its main effects.