Models of a protoplanetary disk forming in-situ the major Uranian satellites before the planet is formed (1901.06448v2)

Abstract: We fit an isothermal oscillatory density model of Uranus' protoplanetary disk to the present-day major satellites and we determine the radial scale length of the disk, the equation of state and the central density of the primordial gas, and the rotational state of the Uranian nebula. This disk does not at all look like the Jovian disk that we modeled previously. Its rotation parameter that measures centrifugal support against self-gravity is a lot smaller ($\beta_0=0.00507$), as is the radial scale length (only 27.6 km) and the size of the disk (only 0.60 Gm). On the other hand, the central density of the compact Uranian core is higher by a factor of 180 and its core's angular velocity is about 2.3 times that of Jupiter's core (a rotation period of 3.0 d as opposed to 6.8 d). Yet, the rotation of the disk is sufficiently slow to guarantee its long-term stability against self-gravity induced instabilities for millions of years.