Вісник Астрономічної школи (Dec 2016)
Former 9th and possible future 9th planet in the Solar system
Abstract
4 terrestrial planets and 4 giant planets were formed in the Solar system. The Main asteroid belt is located between them, and the Kuiper belt and Oort cloud are located beyond the giant planets. Therefore, the planetary system is surrounded by a swarm of rocky-icy bodies up to a distance of 10^5 AU. The former 9th planet in the Solar system, Pluto, is the first known object of the Kuiper Belt. Due to data from the spacecraft “New Horizons” we made significant progress in the study of the physical characteristics of the object and its surface. Numerous observations have shown that the Kuiper belt itself is dynamically stable. And the source of cometary nuclei is a disk scattered by the gravitational perturbation of the giant planets more than 4 billion years ago. Recently, it was reported on indirect evidence of the existence of a new 9th planet in the Solar system with a mass 10 times greater than the mass of the Earth, a distance from the Sun ∼200 AU at perihelion, 600–1200 AU at aphelion, and an orbital period of ∼15000 years. These conclusions are based on the calculation of the orbits of 6 presently known objects of the scattered disc. We pay attention that, in moments close to their discovery, they were located near the perihelion, had a maximum brightness and a maximum orbital velocity. On the basis of probabilistic assumptions, we estimated that the probable number of the same bodies with eccentric orbits should be estimated at many thousands rather than at a few. For the initial evaluation, we used observational data from the Infrared Space Telescope “WISE”. They showed that any Saturn's analog has not been registered at distances up to 30 000 AU. Therefore, a super-Earth with a radius of <11000 km (with a mass of ∼10 Earth masses) would have been seen at a distance up to 1000 AU. Thus, either unknown 9th planet is now at a greater distance, or these results cannot be directly scaled to the super-Earth with a disproportionately lower internal heat reserves.
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