Scientists, including an astronomer of Russian origin, explained under what conditions planets like the Earth or its enlarged copies can form. These observations will facilitate the search for and fixation of potentially habitable planets.
“The results of our research will allow us to reconsider the prevailing view on the timescale of planet formation in numerous stars like the Sun,” explained Eduard Vorobyov, an astronomer from the University of Vienna (Austria) and SFedU in Rostov-on-Don.
In recent years, scientists using the Kepler telescope and ground-based observatories have discovered thousands of planets outside the solar system. Most of them turned out to be the so-called hot Jupiters, large gas giants, as well as rocky planets, the mass of which is one and a half to three times the mass of the Earth.
It is a mystery how the Earth-like planets, which are several times larger in size, are formed, since so far astronomers have not been able to find a single new star system where such planets would arise. This has led many scientists to believe that "super-earths" require exotic formation conditions. However, this contradicts the fact that such exoplanets are most often found near the stars closest to us.
Finally, astronomers have figured out exactly what conditions contribute to the birth of such planets. Researchers have created a gas and dust computer model within which a star and its future satellites are formed. As scientists note, today we understand quite well how giant planets arise and how dust grains appear, but we know almost nothing about what happens after single dust grains combine into relatively small lumps no more than a centimeter in size.
There are several different theories describing this process, the verification of which was impossible due to the lack of information on the behavior of dust in such conditions. Once this data was obtained, scientists began to search for an explanation of how dust and cosmic pebbles turn into larger objects from which planets can form.
By changing various properties of the computer model, including the viscosity of matter and its mixing, astronomers unexpectedly discovered that dust and planets begin to form not several hundred thousand or millions of years after the start of the process of star birth, as planetary scientists previously believed, but immediately after the appearance of the embryo luminaries.
Dust grains remain small - less than a micrometer - in most protoplanetary disks and begin to coalesce into larger objects only if the viscosity of the matter remains low enough. In this case, in the immediate vicinity of the star, already in the first several hundred thousand years, a huge number of cosmic cobblestones with a diameter of up to a meter may appear, whose total mass will be hundreds of times greater than the earth's. This significantly increases the chances that some of them will have time to unite into large rocky planets before the gas giants begin to devastate the star system, absorbing gas and throwing out the embryos of such lands outside of it. If such planets do form, they will concentrate in orbits located at a short distance from the star.
Promotional video:
These models, scientists hope, will help us understand how often super-Earths form in stars similar to the Sun, and how many of them are inside the so-called zone of life.
Irina Tikhonova