11:15 〜 11:30
[PPS07-08] 絡まり構造をもつ高空隙ダストの衝突・圧縮によるエネルギー散逸
キーワード：微惑星形成、繊維ダスト、衝突、圧縮
The current model of planetesimal-formation process is based on the collisional growth of tiny monomers whose typical size is sub micrometers. However, it is not very easy to form planetesimals only by simple mutual collisions of dust aggregates consisting of tiny monomers. Particularly, highly porous structure of dust aggregates must be kept during the collisional growth to prevent bouncing/fragmentation. To overcome this difficulty, we consider the effect of fibrous monomers.
When we look around us, we realize that dust on the floor and corners in the room can grow to a visible (macroscopic) size keeping highly porous structure. By careful inspection of the formed dust, one can confirm that hair and fiber debris play a crucial role to sustain the porous structure.
Based on this simple observation, we consider similar phenomena might govern the planetesimal formation as well. If there were fibrous materials as monomers constructing dust aggregates, entanglement of the fibrous materials would help the dust- aggregate growth also in space.
In this study, we focus on revealing the effect of fibrous materials on the aggregate-growth process and by performing simple laboratory experiments to characterize fundamental mechanical properties. We prepared a set of thin silk threads as starting materials and sucked them by a vacuum cleaner. By this simple procedure, we succeeded to form porous cm-sized dust aggregates (Φ=1.0×10-2) formed by fibers.
We developed a simple experimental system by which a free-fall collision of a dust aggregate onto a flat floor under the vacuum condition (0.2 atm). The collisional dynamics of the dust aggregate was captured by a high-speed camera. Based on the image analysis of the acquired data, we found that COR (Coefficient of Restitution) is almost constant. Statistic compression cycle test was also performed by a universal testing machine in the range of compression force of 0.004-0.006 N. In the compression cycle curves, we found a hysteresis feature indicating approximately 70 % of compression energy was dissipated even by the static compression. We consider the low porosity of fibrous dust is consistent with the concept of fluffy dust which is theoretically suggested to overcomes the obstacles of dust growth to planetesimals. This research implies that fibrous dust presents a useful model for experimentally reproducing fluffy dust aggregates within a laboratory setting, offering valuable insights for estimating timescales of planetesimal formation in protoplanetary disks in future studies.
When we look around us, we realize that dust on the floor and corners in the room can grow to a visible (macroscopic) size keeping highly porous structure. By careful inspection of the formed dust, one can confirm that hair and fiber debris play a crucial role to sustain the porous structure.
Based on this simple observation, we consider similar phenomena might govern the planetesimal formation as well. If there were fibrous materials as monomers constructing dust aggregates, entanglement of the fibrous materials would help the dust- aggregate growth also in space.
In this study, we focus on revealing the effect of fibrous materials on the aggregate-growth process and by performing simple laboratory experiments to characterize fundamental mechanical properties. We prepared a set of thin silk threads as starting materials and sucked them by a vacuum cleaner. By this simple procedure, we succeeded to form porous cm-sized dust aggregates (Φ=1.0×10-2) formed by fibers.
We developed a simple experimental system by which a free-fall collision of a dust aggregate onto a flat floor under the vacuum condition (0.2 atm). The collisional dynamics of the dust aggregate was captured by a high-speed camera. Based on the image analysis of the acquired data, we found that COR (Coefficient of Restitution) is almost constant. Statistic compression cycle test was also performed by a universal testing machine in the range of compression force of 0.004-0.006 N. In the compression cycle curves, we found a hysteresis feature indicating approximately 70 % of compression energy was dissipated even by the static compression. We consider the low porosity of fibrous dust is consistent with the concept of fluffy dust which is theoretically suggested to overcomes the obstacles of dust growth to planetesimals. This research implies that fibrous dust presents a useful model for experimentally reproducing fluffy dust aggregates within a laboratory setting, offering valuable insights for estimating timescales of planetesimal formation in protoplanetary disks in future studies.