Larger dust aggregates less likely to stick together, could challenge planet formation theories

Cosmic dust aggregates, tiny particles that play a crucial role in the formation of planets, have an interesting behavior during collisions depending on their size.

Researchers from Tohoku University conducted numerical simulations of dust aggregate collisions, focusing on microparticles ranging from 10,000 to 140,000 microns in size. They found that as the size of these aggregates increased, their ability to stick together after a collision decreased.

Understanding the process of colliding microparticle aggregates sticking together is essential for comprehending how planets evolve. The current evidence suggests that dust particles collide and aggregate to form larger dust aggregates, which may eventually merge to develop into planets.

The researchers used a discrete modeling system that treated each particle within the aggregate individually, and their soft-sphere simulation allowed for particle deformations during collisions. The results showed that the sticking probability of aggregates reduced as their radius increased.

This finding poses challenges to the theory of planet formation. The adhesive growth of dust clumps is a crucial process in the formation of kilometer-sized bodies known as planetesimals, which are the building blocks of planets. If large dust clumps have difficulty adhering to each other, it could impede the formation of planetesimals and, consequently, planet development through collisional merging via mutual gravity.

The reason why the size of aggregates affects sticking probability during a collision remains unclear. Future studies may investigate the packing structure of aggregates over time and the contact sites between aggregates after a collision to gain more insights.

Furthermore, the researchers plan to conduct simulations with more realistic procedures, including aggregates prepared through laboratory experiments. They also aim to study larger aggregates to challenge and potentially modify existing theories of planet development.

In conclusion, the research on cosmic dust aggregates and their behavior during collisions provides valuable insights into the initial stages of planet formation and the challenges faced in the formation of planetesimals. By studying these processes, scientists hope to gain a deeper understanding of the evolution of planets in the cosmos.

Source: Tohoku University

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