Rare meteorites from the early days of the solar system have indicated that Jupiter was born unexpectedly late, about 5 million years after the birth of the sun and the first asteroids, scientists say in an article published in Science Advances.
“We have shown that the birth of Jupiter must have“stirred up”the asteroid belt in a special way and made the asteroids in it collide at a very high speed necessary for the formation of CB chondrites. Thus, we can say that these meteorites are the first example of how the solar system felt the terrifying power of Jupiter on its skin,”said Brandon Johnson from Brown University (USA).
Conductor of the Solar System
Scientists today believe that the solar system began to form about 4.6 billion years ago as a result of the gravitational collapse of a giant interstellar molecular cloud. Most of the matter went to the formation of the star - the Sun, and from the rest of the matter that did not fall into the center, a rotating protoplanetary disk was formed, from which the planets, their satellites, asteroids and other small bodies of the solar system later arose.
Previously, it was believed that all the planets formed in approximately the same orbits where they are now. Astronomers today believe that Jupiter and other giant planets were "sculptors" whose migrations towards the Sun and the outskirts of the Solar System orchestrated the formation of the "embryos" of the Earth and other rocky planets and their interactions with each other.
Johnson and his colleagues found out when this process began and when Jupiter arose by studying relatively rare meteorites, debris of the oldest asteroids formed as a result of the most powerful "cosmic accidents" in the solar system.
These "celestial stones", the so-called CB-chondrites, are porous rocky structures similar to pumice, containing many balls of an alloy of iron and nickel, which is extremely unusual for this type of asteroid.
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Chondrites, according to scientists today, were formed in the first days of the life of the solar system, at a time when planets, comets and other small celestial bodies did not yet exist. As a rule, chondrites rarely contain metals, since they never survived heating to high temperatures and did not melt.
Dance of the little chondrites
CB chondrites are an exception in this respect - they contain a record high proportion of metals for asteroids of this type. Therefore, many astronomers believe that they are not actually chondrites, since it is extremely difficult to explain the appearance of metal balls in them using generally accepted theories of the birth of the solar system.
“The evaporation of iron in meteorites can occur only at very high collision speeds. You need to accelerate it to a speed of 20 kilometers per second just to start thinking about it, and the usual models of the forming solar system, at best, “accelerate” asteroids only up to 12 kilometers per second,”explains the planetary scientist.
Johnson found the answer to this riddle by studying the structure of metal balls in such meteorites. He found that they all formed about five million years after all other types of chondrite matter had arisen.
Such a synchronous appearance of CB-chondrites prompted him to think that the impetus for their birth, in the literal and figurative sense, could have been the migrating Jupiter, which “shuffled” the deck of nascent asteroids and made them collide with each other.
He tested this idea by creating a computer model of the newborn solar system, in which Jupiter migrated towards the Sun in the first few million years of its life. She showed that its motion was enough to cause even large enough protoplanetary bodies, whose diameter was 90 or 300 kilometers, to collide with each other at very high speeds, reaching 33 kilometers per second.
Such collisions did not last very long - about 500 thousand years. Accordingly, we can say that Jupiter was born virtually simultaneously with the formation of CB-chondrites - about 5 million years after the first asteroids began to form in the Solar System after the birth of the Sun.
This time of birth of Jupiter was a big surprise for Johnson and his colleagues - earlier scientists believed that giant planets arose very quickly, since the gas of the protoplanetary disk was supposed to dissipate under the pressure of the rays of the young Sun. If the calculations of the authors of the article are correct, then this was not the case, which could force scientists to reconsider the theory of the birth of the solar system.