Formation of satellites in circumplanetary discs generated by disc instability

Abstract

ABSTRACT We investigated the formation and evolution of satellite systems in a cold, extended circumplanetary disc (CPD) around a 10MJupiter gas giant, which was formed by gravitational instability at 50 au from its star. The disc parameters were from a 3D global smoothed particle hydrodynamics simulation. We used a population synthesis approach, where we placed satellite embryos in this disc, and let them accrete mass, migrate, collide until the gaseous disc is dissipated. In each run, we changed the initial dust-to-gas ratio, dispersion- and refilling time-scales within reasonable limits, as well as the number of embryos and their starting locations. We found that most satellites have mass similar to the Galilean ones, but very few can reach a maximum of 3MEarth due to the massive CPD. Large moons are often form as far as 0.5Rdisc. The migration rate of satellites are fast, hence during the disc lifetime, an average of 10MEarth worth of moons will be engulfed by the planet, increasing greatly its metallicity. We also investigated the effect of the planet’s semimajor axis on the resulting satellite systems by rescaling our model. This test revealed that for the discs closer to the star, the formed moons are lighter, and a larger amount of satellites are lost into the planet due to the even faster migration. Finally, we checked the probability of detecting satellites like our population, which resulted in a low number of ≤ 3 per cent even with upcoming powerful telescopes like E-ELT.