Simulations reveal how dust reaches the circumplanetary disk of PDS 70 c

The formation of moons around giant planets depends on how these planets pull gas and dust from the surrounding disk. By modeling the young star PDS 70, researchers have investigated how material flows toward the planet PDS 70 c. The results show that large planets act as a filter, significantly changing the amount and size of dust that can actually reach the planet's own miniature disk, known as a circumplanetary disk.

To understand this process, researchers used complex three-dimensional computer simulations of gas and dust movement. They examined planets with masses equal to one and two and a half times the mass of Jupiter. These models included different sizes of dust particles to track how they move from the outer disk inward.

The findings show that a pressure trap at the edge of the planet's orbital gap blocks most large dust particles. Only small grains are able to flow efficiently toward the planet. While this filtering process reduces the overall amount of dust, the constant inflow of these small grains is enough to form a system of moons similar to the Galilean satellites of Jupiter within a few million years.

Because more massive planets block larger grains more effectively, the dust that does reach the planet is mostly composed of very small particles. This means that observations of these disks using millimeter-wave light may underestimate the total amount of dust present if the particles are not growing in size.

Key findings
- Giant planets act as filters that block larger dust particles from reaching their circumplanetary disks.
- Only dust grains smaller than 61 micrometers for a 1 Jupiter-mass planet or 10 micrometers for a 2.5 Jupiter-mass planet accrete efficiently.
- The amount of dust reaching the planet is about 100 times lower than in the outer disk.
- Continuous inflow of small grains is sufficient to build a moon system within a few million years.
- Current methods for measuring disk mass using millimeter-wave light may require adjustment due to the dominance of small, low-opacity dust particles.

Scientific study

Feeding the Circumplanetary Disk: 3D Simulations of Dust Filtration and Accretion in PDS 70 c (external link)