Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS08] Planetary Sciences

Mon. May 21, 2018 1:45 PM - 3:15 PM International Conference Room (IC) (2F International Conference Hall, Makuhari Messe)

convener:Takaya Okamoto(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Kenji Kurosaki(Department of Physics, Nagoya University), Chairperson:Sirono Sin-iti(名古屋大学 大学院環境学研究科), Kobayashi Hiroshi(名古屋大学大学院 理学研究科)

2:15 PM - 2:30 PM

[PPS08-21] Tensile Strength of Porous Dust Aggregates Measured with Dust N-body Simulations

*Misako Tatsuuma1,2, Akimasa Kataoka2, Hidekazu Tanaka3 (1.The University of Tokyo, 2.National Astronomical Observatory of Japan, 3.Tohoku University)

Keywords:Protoplanetary disks, Planetesimals, Comets, Tensile Strength

In protoplanetary disks, formation process of µm-sized dust grains into km-sized planetesimals has several theories such as direct coalescence growth and concentration due to instability, and has not yet been unraveled. Also, we cannot directly observe planetesimals and restrict the formation process by observation of protoplanetary disks and exoplanets. Therefore, we focus on comets which are the most primitive objects in the solar system and are thought to be survivors of planetesimals. In recent years, tensile strength has been measured by the search results of comet 67P/Churyumov-Gerasimenko in the solar system. The tensile strength of planetesimals depends on their composition and formation process, and by investigating the tensile strength, the planetesimal formation process can be confined. Moreover, tensile strength is applicable not only to the planetesimal formation process but also to calculations of collisional destruction of dust grains and planetesimals.

Therefore, we conducted an N-body calculation considering the direct interaction of dust particles (Wada et al. 2007, ApJ, 661, 320) and investigated the tensile strength of porous dust aggregates. The dust aggregates as the initial condition were assumed to be ice with 0.1-µm-sized constituent particles and compressed by simulating their formation process (Kataoka et al. 2013, A&A, 554, A4). Also, though comets are considered to be sintered, in this research we assumed the case without sintering as the first step. As a result of the numerical calculation, tensile stress gradually increases as tensile displacement increases, and the tensile stress takes the maximum value at the time when the volume filling factor decreases to about a half of the initial value. In other words, the tensile strength was obtained. It was also confirmed that cutting of contacts between particles in dust aggregates begins to occur near the maximum tensile stress. The tensile strength is ~ 7×103 Pa when the initial volume filling factor is 0.1. This value is about 14 times larger than the compressive strength ~ 5×102 Pa when the volume filling factor is 0.1. This indicates that dust aggregates have a property that can withstand tension rather than compression. This difference can be explained by the fact that the compression of dust aggregates proceeds with rolling displacement between particles with a relatively weak stress, whereas the tensile strength is determined by the cutting of contacts between particles which requires a strong stress. In this talk, we will also discuss the dependence of tensile strength on the initial volume filling factor and on particle interaction model.