5:15 PM - 6:45 PM
[MGI29-P05] Global N-body simulation of planetary formation: Outward migration of protoplanets through Planetesimal-Driven Migration
Keywords:Planetary formation, Planetary migration, N-body simulation
In classical planet formation theory, planetary migration was not considered, and it was assumed that planets formed in situ. However, it is known that assuming in situ formation poses challenges in explaining the formation of Uranus and Neptune at the outer edges of the solar system within the age of the solar system. In addition, since the discovery of the first exoplanet in 1995, over 5000 exoplanets have been confirmed. Among these, there are many planets, such as Hot Jupiters with orbital periods of just a few days which cannot be explained without considering planetary migration.
The leading mechanisms of planetary migration include Type I migration, where planets migrate due to gravitational interactions with a gas disk, and planetesimal-driven migration (PDM), resulting from gravitational scattering between a planet and planetesimals. In Type I migration, planets typically lose their angular momentum and drift inwards, a phenomenon known as “planet migration problem”. Conversely, in PDM, it has been suggested that planets can universally migrate outwards by gaining angular momentum from planetesimals. However, due to the high computational cost, previous studies of PDM ignored gas drag and gravitational interactions among planetesimals, leaving it unclear whether planets can migrate dynamically through PDM.
In this study, we used a parallel N-body simulation code for planetary system formation, GPLUM, and the supercomputer Fugaku to conduct the first-ever self-consistent global N-body simulation of PDM in which gravitational interactions among planetesimals, gas drag, and Type-I migration are taken into account. In our simulations, we placed a single protoplanet within a planetesimal disk and conducted a total of 570 simulations with varying parameters such as the mass of the protoplanet, the number of particles, and the presence of gas drag and Type I migration to statistically investigate the impact of PDM on the planet migration process.
Through our simulations, we found that a fair fraction of protoplanets are capable of migrating outward within the disk despite experiencing inward kick due to Type I torque. Furthermore, our results show that PDM can cause dynamic migration of protoplanets within the disk, even at a much smaller mass ratio between a protoplanet and planetesimals than previously thought. Our results not only suggest a solution to the longstanding “planet migration problem”, but they also indicate that planets can grow while migrating actively inwards and outwards within the disk.
In this presentation, we will present the results of our self-consistent N-body simulations of PDM and discuss the effect of PDM on the process of planet migration.
The leading mechanisms of planetary migration include Type I migration, where planets migrate due to gravitational interactions with a gas disk, and planetesimal-driven migration (PDM), resulting from gravitational scattering between a planet and planetesimals. In Type I migration, planets typically lose their angular momentum and drift inwards, a phenomenon known as “planet migration problem”. Conversely, in PDM, it has been suggested that planets can universally migrate outwards by gaining angular momentum from planetesimals. However, due to the high computational cost, previous studies of PDM ignored gas drag and gravitational interactions among planetesimals, leaving it unclear whether planets can migrate dynamically through PDM.
In this study, we used a parallel N-body simulation code for planetary system formation, GPLUM, and the supercomputer Fugaku to conduct the first-ever self-consistent global N-body simulation of PDM in which gravitational interactions among planetesimals, gas drag, and Type-I migration are taken into account. In our simulations, we placed a single protoplanet within a planetesimal disk and conducted a total of 570 simulations with varying parameters such as the mass of the protoplanet, the number of particles, and the presence of gas drag and Type I migration to statistically investigate the impact of PDM on the planet migration process.
Through our simulations, we found that a fair fraction of protoplanets are capable of migrating outward within the disk despite experiencing inward kick due to Type I torque. Furthermore, our results show that PDM can cause dynamic migration of protoplanets within the disk, even at a much smaller mass ratio between a protoplanet and planetesimals than previously thought. Our results not only suggest a solution to the longstanding “planet migration problem”, but they also indicate that planets can grow while migrating actively inwards and outwards within the disk.
In this presentation, we will present the results of our self-consistent N-body simulations of PDM and discuss the effect of PDM on the process of planet migration.