10:45 AM - 12:15 PM
[MGI30-P04] N-body simulation of planetary formation through pebble accretion in a radially structured protoplanetary disk
Keywords:Planetary formation, Pebble accretion, N-body simulation
In this presentation, we will present the results of our planetary N-body simulations and discuss the possibility of the formation of Solar System-like planetary system in radially structured PPDs (protoplanetary disks).
In the conventional theory of planet formation, it is assumed that PPDs are axisymmetric and have a smooth radial profile. However, recent radio observations of PPDs have revealed that many of them have complex radial structures. In addition, the occurrence of magnetorotational instability (MRI) was found theoretically in the early 1990s, indicating that the structure of PPDs is much more complex than what was assumed in the conventional theory. More recently, it has been pointed out that turbulence originating from MRI does not occur or is suppressed in certain regions of PPDs. This region is called the dead zone and is a laminar structure. In such a disk with a dead zone, a pressure bump forms at the boundary of the dead zone, causing dust to accumulate. To summarize, planetary system formation in PPDs is now being actively studied in both theoretical and observational aspects. Thus, in our research, we performed a series of N-body simulations to investigate how planets are formed in PPDs with radial structures. In our model, we assumed a steady-state PPD model and solved the dust growth in the disk. Once the dust mass reaches the critical mass, it starts to accrete onto the central region of the disk due to the effect of the gas drag. The accreting dust is expressed with superparticles and their gravitational and collisional evolutions are solved in our N-body simulation.
In our simulation, the dust accretion halts when it reaches the discontinuity boundary within the terrestrial-planet forming region (~0.6AU) and thus planet formation actively proceeds at the boundary. The final mass of the protoplanet becomes the Earth mass within ~104 years. We also confirmed that giant collisions of protoplanets occur universally in our model. Moreover, we found that multiple planets form at regular intervals in the vicinity of the discontinuity boundary. These results indicate the possibility of the formation of Solar System-like planetary systems in radially structured PPDs.
In the conventional theory of planet formation, it is assumed that PPDs are axisymmetric and have a smooth radial profile. However, recent radio observations of PPDs have revealed that many of them have complex radial structures. In addition, the occurrence of magnetorotational instability (MRI) was found theoretically in the early 1990s, indicating that the structure of PPDs is much more complex than what was assumed in the conventional theory. More recently, it has been pointed out that turbulence originating from MRI does not occur or is suppressed in certain regions of PPDs. This region is called the dead zone and is a laminar structure. In such a disk with a dead zone, a pressure bump forms at the boundary of the dead zone, causing dust to accumulate. To summarize, planetary system formation in PPDs is now being actively studied in both theoretical and observational aspects. Thus, in our research, we performed a series of N-body simulations to investigate how planets are formed in PPDs with radial structures. In our model, we assumed a steady-state PPD model and solved the dust growth in the disk. Once the dust mass reaches the critical mass, it starts to accrete onto the central region of the disk due to the effect of the gas drag. The accreting dust is expressed with superparticles and their gravitational and collisional evolutions are solved in our N-body simulation.
In our simulation, the dust accretion halts when it reaches the discontinuity boundary within the terrestrial-planet forming region (~0.6AU) and thus planet formation actively proceeds at the boundary. The final mass of the protoplanet becomes the Earth mass within ~104 years. We also confirmed that giant collisions of protoplanets occur universally in our model. Moreover, we found that multiple planets form at regular intervals in the vicinity of the discontinuity boundary. These results indicate the possibility of the formation of Solar System-like planetary systems in radially structured PPDs.