(ORDO NEWS) — Modern observational data on the physicochemical composition of the planets and the comet-asteroid component make it possible to propose the following most probable scenario for their formation during the formation of the Sun and the solar system itself.
About 10 billion years ago, the protostellar cloud, from which the Sun and planets were subsequently born, was a quasi-spherical formation, consisting of 75% hydrogen and 25% helium-4, and all other elements accounted for only an insignificant part of the mass of the cloud.
Nevertheless, despite the relatively small contribution to the density of protostellar matter, the role of these heavy elements was decisive in the dynamics of matter cooling. Physicists and chemists are well aware of the fact that the higher the atomic number of a chemical element, the easier it is to excite its electron shell.
This excitation is accompanied by the emission of electromagnetic radiation quanta, which carry away the energy expended on excitation of the atom. Actually, this mechanism determines the thermal regime of the protosolar cloud, leading to a decrease in its temperature.
Along with cooling, the protosolar cloud is compressed under the influence of its own gravity of the substance, accompanied by an increase in density in the center of the cloud.
An increase in density leads to heating of the central part of the cloud to superhigh temperatures, when it is possible to “switch on” the reactions of thermonuclear fusion of elements.
At the same time, a balance is established between gravity and pressure of matter in the central part of the cloud, which characterizes the first phase of the formation of our Sun.
And what happens at the periphery of the protosolar cloud during this period? Numerous calculations and computer experiments allow us to conclude that, at the core formation phase, the outer regions of the cloud have a complex multiphase structure.
First of all, in the region of the core, a zone of accretion (leakage) of the surrounding matter appears on the central formation, leading to an increase in its mass. The energy released as a result of the compression of the core forms a region of strong ionization, which expands towards the periphery of the cloud.
Under the action of radiation, the matter is “blown out” to the periphery and is collected in a dense shell – a dust cocoon, extending up to the outer boundary of the cloud.
In this case, the relatively weak rotation of the protostellar cloud at the beginning of the compression will intensify as the dense central zone is formed and lead to the flattening of the entire system into a toroidal formation.
Computer modeling makes it possible to single out several characteristic stages of this process. In the first (1) phase, the balance between gravity, pressure and rotation of the matter leads to the formation of a thick, and then more and more flattening disk.
Further, in the disk, the substance is fragmented into dust clots (2-3). After about a million years, dust clumps stick together into compact asteroid-sized bodies with a physicochemical composition close to dusty (4).
After that, for about another 100 million years, the swarm of asteroids experiences intense mixing, accompanied by the fragmentation of larger objects and the unification (gluing) of small ones. At this phase (5), the embryos of the terrestrial planets – Mercury, Venus, Mars and the Earth – are actually formed.
After that, for about another 200 million years (6), the planets of the Jupiter group formed, accreting gas onto themselves, not included in the less massive terrestrial planets.
And finally, after another 1 billion years, the most distant planets from the Sun are formed – Neptune and Pluto, completing the process of formation of the solar system as a whole.
From this scenario, it becomes clear that asteroids and comets are the remnants of a swarm of protoplanetary bodies, moreover, asteroids are rocky formations of the inner near-solar zone that gave rise to terrestrial planets, and comets are rock-ice formations genetically associated with the zone of giant planets.
But it is most noteworthy that in the process of formation of the planets of the Jupiter group, the giant planets Jupiter and Saturn played the role of a kind of “cleaner” of the solar system, throwing small protoplanetary clumps to the far periphery of the solar system with their gravitational field.
Thus, the solar system turned out to be surrounded by a swarm of rock-ice bodies, extending over distances from 20,000 to 200,000 radii of the Earth’s orbits around the Sun (how not to be surprised by the “special”
It is curious that back in 1950, the outstanding Dutch astronomer Jan Oort, analyzing the orbits of 19 long-period comets, long before the era of computer simulation and the unmanned mission to Halley’s comet, suggested the need for the existence of a commentary belt on the periphery of the solar system.
Over the past 50 years, the list of known comets has increased by almost an order of magnitude, and their trajectories are in perfect agreement with ideas about the existence of the comet belt. Further, following tradition, we will call this cometary belt of the solar system the “Oort cloud”.
How massive is the Oort cloud? According to modern data, its mass turns out to be very small – approximately 10% of the mass of the Earth falls on one hundred billion comet nuclei.
From here it is easy to determine the mass of a “typical” cometary nucleus – about one hundred billion tons, although in the world of comets there are both “dwarfs” (weighing up to a billion tons) and “giants” (up to one hundred thousand billion tons!).
However, both “dwarfs” and “giants” move in the solar system along elliptical orbits, in full accordance with the laws of mechanics and the theory of gravity. The same laws predict that the orbits of comets are stable, i.e. like planets, comet nuclei make their cycle on the periphery of the solar system in the Oort cloud.
But then why do we meet them in the inner regions of the solar system? To answer this question, we need to take the next step in understanding the structure of the solar system and its place in our galaxy.
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