On the formation of satellites in dense solid-particle disks

Abstract

Single massive satellites are of great observational interest, as they can produce prominent and potentially detectable signatures. For terrestrial planets and super-Earths, giant impacts in the late stages of formation may generate dense self-gravitating disks — favourable environments for the formation of such satellites. Motivated by this, we explore satellite formation in dense solid-particle disks through three-dimensional N-body simulations, focusing on the effects of disk mass and the surface density exponent ($\beta$). Our results reveal significant variability in the masses and configurations of satellites formed under identical disk parameters, highlighting the stochastic nature of the process. Higher disk masses and flatter surface density profiles favour the formation of more massive satellites. Disks with masses above 0.03 planetary masses typically yield a single dominant satellite, while those between 0.003 and 0.03 tend to form two-satellite systems. On average, the mass of the largest satellite scales linearly with the initial disk mass, in agreement with analytical predictions. We estimate that a disk with a minimal mass of 0.03 planetary masses around a 1.6 Earth-mass planet orbiting a Sun-like star could form an Earth–Moon-like system detectable by telescopes with a photometric precision of 10 parts per million – a level achievable by the James Webb Space Telescope.