Previous theories suggested that giant planets were formed by collisions and accumulations of planetesimals and the subsequent accretion of gas over millions of years. However, these models do not explain the existence of gas giants located far from their stars and the formation of Uranus and Neptune.
A new model developed by the astrophysics department at LMU, the ORIGINS cluster, and the Max Planck Institute for Solar System Research (MPS) includes all the essential processes that play a vital role in planet formation.
Scientists used this model to show that annular perturbations in protoplanetary disks, so-called substructures, can trigger the rapid formation of multiple gas giants. The study’s results agree with recent observations and suggest that giant planets might form faster and more efficiently than we thought.
When a planet grows big enough to affect the gas disk around it, it pushes dust outward, like a sheepdog herding sheep, to regions beyond its orbit.
Using their model, scientists have shown- how aerodynamically, tiny dust particles gather in the turbulent gas disk and how this initial disruption in the disk retains dust, preventing it from dissipating towards the star.
Because there is suddenly a lot of “building material” accessible in a small space and the ideal circumstances for planet formation are met, this accumulation makes the formation of planets extremely efficient.
Til Birnstiel, Professor of Theoretical Astrophysics at LMU and member of the ORIGINS Cluster of Excellence, said, “When a planet gets large enough to influence the gas disk, this leads to renewed dust enrichment farther out in the disk. In the process, the planet drives the dust – like a sheepdog chasing its herd – into the area outside its orbit.”
Tommy Chi Ho Lau, lead author of the study and doctoral candidate at LMU, said, “The process begins anew, from inside to outside, and another giant planet can form. This is the first time a simulation has traced the process whereby fine dust grows into giant planets.”
The study suggests that in other planetary systems, a disturbance can trigger planet formation at much greater distances and still occur quickly. The ALMA radio observatory has often observed young systems with gas giants beyond 200 AU. The model also explains why our solar system stopped forming planets after Neptune: the available building material was exhausted.
The study supplements recent research on early planetary systems with unique disk properties essential for planet formation. It suggests that giant planets’ formation occurs more rapidly and efficiently than previously thought. These insights offer a better understanding of how massive planets form in our solar system and clarify the variety of planetary systems we observe.
Journal Reference:
- Tommy Chi Ho Lau, Til Birnstiel, Joanna Dra̧żkowska , Sebastian Stammler. Sequential giant planet formation initiated by disc substructure. Astronomy & Astrophysics. DOI: 10.1051/0004-6361/202450464
