Translated material
Earth as a quirk of astrophysics
The solar system may turn out to be a unique object in the Universe
The first people to fly into space were amazed at what an incredible miracle of miracles the Earth appears from orbit. These are, of course, emotions, but it turned out that even from the point of view of astrophysics, our planet is seen, if not a unique phenomenon, then at least very rare. Its favorable location in the solar system allowed a full-fledged biosphere to appear on the planet in a few billion years. Confirmation of the hypothesis of the unusualness of circumsolar planets was attempted by Edward Tommes from the Canadian University of Guelph in the province of Ontario and Soko Matsumura and Frederic Razio from Northwestern University in Illinois, USA.These specialists were engaged in computer modeling of the genesis of planets in the first millions of years of the life of the star system. This is a fairly common matter, but very difficult - many factors must be taken into account. Modeling requires powerful machines that calculate the movement of gas clouds and a lot of time. Tomms and his colleagues risked simplifying their task by breaking the system into parts: the disk of gas and dust around the young star was divided into separate rings, each of which was calculated separately, for the convenience of the model. In this case, data was used on more than three hundred exoplanets known to scientists (planets orbiting distant stars) and about a hundred parameters (the amount of gas, its density, “viscosity”, etc.).
It was possible to calculate a period of about 10 million years. If we equate the life of a star with the life of a person, then these are, perhaps, the first seconds after the birth of a baby. However, if a child only manages to scream during this time, an entire planetary system can be born, develop and die in the circumstellar disk.
The model included a variety of different combinations of parameters, but in the vast majority of cases, what scientists got as a result did not in any way resemble the Solar System. It turned out that it is extremely difficult for the Universe to create something even remotely reminiscent of the environs of our Earth, where small rocky planets are located in inner orbits, then gas giants and, finally, frozen celestial bodies of different sizes at the edges. The standard scheme is completely different: either “hot Jupiters” or many small planets.
“Hot Jupiters” is the common name for huge exoplanets that, like Saturn or Jupiter, are made of gas but are located very close to their parent star. According to the Tomms-Matsumura-Rezio model, if at the birth of a star a lot of excess building material remains in the system, then several such planets are formed in it, which then begin to gradually approach their sun. All this is accompanied by a fierce “struggle for gas”: heavy “hot Jupiters” try to attract as many molecules dangling in space as possible. In addition, the forces of mutual attraction between the giants bend their orbits. Some of the “Jupiters” can get so close to the star that they will eventually be absorbed by it or thrown out of the planetary system by the gravity of the star.
The surviving planets will begin to move in highly elongated elliptical orbits, either approaching the star or moving far away from it, which is not at all similar to our planetary system, where large celestial bodies move around the Sun in almost circular orbits. Even if a small dense planet suddenly formed near the star, then, undoubtedly, it would not have a single chance of surviving in an orbit close to the star - the planet would sooner or later be swallowed up by such a “hot Jupiter”.
Another option is a star with a small amount of gas. In this case, the model predicted the formation of several small terrestrial planets. At the periphery of the system, a local analogue of Neptune may form - a frozen gas planet. And that's it - no gas giants. This scheme may be more promising for the search for alien life, but it is also not at all similar to the Solar System.
For the simultaneous birth of Earth, Venus, Jupiter, Uranus, etc. many different factors must come together. According to Edward Tommes, there is a very narrow window of parameters when, after the birth of a star, something similar to the solar system is obtained. If the model created by scientists truly reflects reality, then this means that humanity is very lucky. At the time of its birth, the Sun would have had a little more or a little less gas around it, and life on Earth would not have happened. We can rejoice for the quirk of cosmogony that gave us the chance for the existence of protein bodies. On the other hand, since there are few systems like ours, the likelihood of the presence of alien life is reduced. That is, meeting with terrible “strangers”, whom modern man fears more than nuclear war, becomes even less likely.