(ORDO NEWS) — Astronomers using computer simulations determined that the dwarf planet Ceres was formed not in the main asteroid belt, but beyond the orbit of Saturn, from where it could migrate into the inner solar system due to interactions with giant planets and protoplanets.
In this case, it is a large planetesimal that is similar to some Kuiper Belt objects. Article published in Icarus magazine.
Ceres is the largest object in the main asteroid belt, which is characterized by a number of interesting properties. Its mass is about 0.33 percent of the total mass of the Main Belt, while the dwarf planet has a low density and low albedo, which is similar to carbonaceous chondrites.
Ceres’ position in the Main Belt is close to many C-type asteroids, but the planet is not one of them. Ceres is more similar to G-type asteroids, has a partially differentiated structure, and consists of a water-ice-rich mantle and a rocky core.
Ceres’ properties make it similar to the largest Kuiper belt objects such as Eris, Pluto or Charon, raising questions about the origin of the planet. In particular, the discovery of ammonia ice on the surface of Ceres is considered strong evidence that the dwarf planet formed in the outer solar system, outside the snow line.
Because of this, the hypothesis arose that Ceres could be a planetesimal captured from the outer part of the protoplanetary disk during its interaction with the giant planets described in the Nice model.
A team of planetary scientists led by Rafael Ribeiro de Sousa of the State University of São Paulo has published simulations of the early dynamic evolution of the outer Solar System to determine possible mechanisms for the migration of a Ceres-sized planetesimal into the Main Asteroid Belt from beyond orbit of Saturn.
Scientists have determined that the proportion of the population of Ceres-sized planetesimals that fall into the Main Asteroid Belt ranges from 2.8×10–5 to 1.2×10–3, depending on the initial position of the object in the outer part of the circumstellar disk.
The captured bodies had a 70 percent chance of having an orbital semi-major axis between 2.5 and 3 astronomical units, a 33 percent chance of an eccentricity of less than 0.2, and a 45 percent chance of an orbital inclination of less than 10 degrees.
Considering that earlier estimates predicted the existence of 3,600 Ceres-sized planetesimals in the circumstellar disk beyond Saturn’s orbit, the probabilities of capturing a Ceres-sized body into the Main Belt are 15, 34, and 51 percent for the inner, middle, and outer parts. belts, respectively.
The very process of migration and capture of Ceres into the Main belt took place in several stages. First, there was a phase of rapid mixing of planetesimals in the outer protoplanetary disk due to scattering processes.
The Ceres candidate would then come into mean-motion resonance with the giant planets, after which it could collide with other migrating objects that were able to increase or decrease the eccentricity of its orbit and eject it into relatively stable regions of the inner asteroid belt.
The parameters of the Ceres candidate’s orbit could also be affected by friction from the gas in the disk. At the final stage, the gas dissipated from the protoplanetary disk, and other external objects were removed, leaving Ceres in a stable orbit in the Main Belt.
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