How do planets form? A crucial step is the transformation of tiny dust particles into kilometer-sized planetesimals. We recently reveals how dust growth could trigger a key process called streaming instability (SI), making planet formation possible in previously unexpected conditions.
Streaming instability acts like a cosmic traffic jam, concentrating dust particles in protoplanetary disks. Traditional models required specific conditions: particles needed to be large enough, or there needed to be enough dust compared to gas. This limited where planetesimals could form.
With the newly developed Athena++ couple with the dust coagulation module, we shows that even when starting with particles too small for SI, natural dust growth through collisions can eventually trigger the process. As particles settle toward the disk's midplane and collide, they grow large enough to initiate SI, leading to dense dust clumps - potential planetesimal precursors. This open new possibilities for understanding planet formation, suggesting it might be a more universal process than once believed.
Showing the dust evolution from sub-millimeter to centimeter sizes. As particles grow larger (top to bottom panels), they form denser clumps through streaming instability, potentially leading to planetesimal formation. Simulations performed using Athena++ code with 101 dust fluid species and coagulation physics.