Academia Sinica Logo

Abstract:

Collisional growth of dust grains is the key step in planet formation, especially in the formation of kilometer-sized objects called planetesimals. Since planetesimals are the building blocks of planets, it is important to understand how and how efficiently planetesimals form. There are several obstacles that limit dust growth, which include fragmentation and dust depletion due to radial drift. Streaming instability has been proposed to bridge the gap to planetesimal formation. According to previous studies, the instability drives dust clumping and create massive clumps from which planetesimals form by gravitational collapse. Although it is promising, the massive clump formation is efficient only if the dust grains are sufficiently large. The required dust sizes are larger than the fragmentation-limited size. Thus, there is still a gap between the initial dust growth and planetesimal formation. To bridge this gap, we examine dust coagulation through moderate-level clumping, which should occur prior to the massive clump formation. In this talk, I will discuss how the clumping promotes dust growth and how this process relaxes the condition for planetesimal formation.