An international team of scientists with the participation of employees of Moscow State University explained the structure of Saturn’s rings and modeled them into a supercomputer. This result can be applied to a variety of systems both in nature and in the industry.
An interesting question – why around some planets, such as Saturn, the rings appear, and others, from the same, say, Earth or Mars, the rings do not have? As it turned out, the size of the planet’s role does not play. The rings were found and the Giants, and even asteroids. An example of the latter – Chariklo asteroid with a diameter of about 260 km, which in the past year, the Spitzer Space Telescope found just two rings.
But if the answer to this question, at least approximately, there – about one of the planets historically proved little dust and some other – a lot. Dust gathered together, formed particles which continue to grow and become more and more of that, of course, understandable. But why, particle growth suddenly stopped when they reached the size of a house? It remained a mystery.
Moreover, the very particle size distribution should have a beautiful mathematical law “inverse cube”, which means, for example, that the particle size of 2 meters in 8 times smaller than the size of the past 1 meter, 3 meters in size – less than 27 times, etc. The nature of this law also presents mysterious.
An international team of researchers, which includes four Russians: a graduate of Moscow State University Nikolai Diamond (Professor of the University of Leicester, UK), Paul Krapivsky (Prof. Boston University, USA) and a researcher at the Department of Polymer and Crystal Physics Faculty of Moscow State University named after MV Lomonosov Anna Bodrov Vladimir Stadnichuk have finally clarify this issue by studying the particle size distribution in the rings of Saturn. During the work, the researchers showed that the observed distribution is universal, that is, common to all the rings arising from celestial bodies, the particles of which have a similar nature. Furthermore, the scientists were able to unravel the mystery of the “magic” of the law “inverse cube.” The relevant article of the collective of authors, which includes Professor Frank Spahn (University of Potsdam, Germany), Jurgen Schmidt (University of Oulu, Finland) and Hisao Hayakawa (Kyoto University, Japan) published in the journal Proceedings of the National Academy of Sciences .
Saturn’s rings are a majestic sight. They consist mainly of ice crumbs, with small patches of minerals and extend for hundreds of thousands of kilometers away.
At the same time, “the thickness of the rings”, that is, their size in the other perpendicular direction, only 10-100 meters! In this sense, the rings of Saturn – a million times “thinner” the sharpest razor. In addition, the whole mass of ice rushing around Saturn with tremendous speed, 72 000 kilometers per hour. This so-called orbital velocity with which particles move integrally. However, the velocity of individual particles still slightly differ from this average speed, but on average, these deviations are negligible – the order of several meters per hour!
As the particles fly up with each other at such low speeds, they are connected and can not fly away again because of surface forces – an effect similar to how two snow stick, providing them with the power to connect together. This process of coalescence of particles occurs constantly. However, there is also the opposite process of destruction of the particle collisions. The fact that a very small fraction of the particles deviation from the average speed is significant.
If such a “fast” particle smashes into his “neighbor”, both crumble into small pieces. This happens very rarely, but, ultimately, set the balance between integration and disintegration of the particles.
Scientists have constructed a mathematical model of the processes that were studied by various methods, including conducting a numerical solution a huge number of differential equations. This can only be done on a supercomputer. The result has been involved one of the most powerful supercomputers in Europe – the MSU supercomputer “Chebyshev”. This part of the work was carried out Moscow colleagues research group. Scientists have explained as the absence of particles in Saturn’s rings more than a certain size, and a mysterious law of “inverse cube.” Moreover, because of the resulting model followed, and the important conclusion that these laws should be observed for all rings, whether it is a ring of the planet or asteroid.
According to the researchers, in particular, explained Anna Bodrov from Moscow State University – this universality is the only well-educated guess. In order to confirm or refute it, more research is required other rings.
This work allows to make a number of other scientific findings – such as the mechanism of formation of the rings and their evolution. In particular, the results of researchers suggest that the rings of Saturn are in steady state. This means that the dinosaurs were observed (if they could observe) the same ring as now. Those rings will monitor our descendants. Moreover, since the characteristic time of the change of rings under the influence of any external influences does not exceed 10 000 years (it also follows from the model), nothing catastrophic happened to the ring since the Bronze Age.
At the time Nobel Prize winner Pyotr Kapitsa said that “there is nothing more practical than a good theory.”
This fully applies to this work. Researchers have developed a highly versatile mathematical tool that can be easily attached to a variety of systems both in nature and in the industry.
Wherever there is a system of particles that can stick together in collisions with low speed and break into small pieces at high speeds, there will be a distribution of particle size following the “magic” law of inverse cube.
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