The space fairy tale-epic "Star Wars", after its appearance more than 40 years ago, has become not only a unique cultural phenomenon, but also an interesting prophecy in the field of astronomy. Only at the beginning of the 21st century did scientists find several exoplanets located in systems of double stars, just like Tatooine, where Anakin Skywalker was born. True, until recently, the mechanism of the emergence of such massive objects remained a mystery - after all, one of the stars should have literally scattered the matter of the protoplanetary disk, preventing planetesimals from forming in it.
Now several planets are known at once orbiting two stars, so we know for sure: something like Tatooine in the real world can exist. The problem is that it is rather difficult to describe the appearance of such bodies in binary stellar systems. As a rule, the smaller luminary plays the role of a "mixer" at the early stages of the formation of the protoplanetary disk. Due to gravitational disturbances, the substance in it moves too fast, and planetesimals cannot form. As a result, gas and dust, at best, stick together into asteroids and comets, and most of the matter just falls on the stars.
The main hypothesis for the appearance of planets in systems of binary stars is the process of capturing "orphans" from the surrounding space (binary systems in this regard are much more effective than single ones). But experts from the Max Planck Institute for Extraterrestrial Physics (Germany) and the University of Cambridge (Great Britain) have a different opinion. The authors of the new scientific work - Roman Rafikov and Kedron Silsbee - have developed a more detailed computer model than previously used. The results of simulations using it will be published in the next issue of Astronomy and Astrophysics.
The difference between the improved model lies in the greater number of parameters of the developing planetary system, which are taken into account. For example, Rafikov and Silsby took into account the gravitational influence of the protoplanetary disk itself on the formation of planetesimals. It turned out that under certain conditions it helps a lot to compensate for the disturbances from the second star.
Earlier, only its deceleration in a relatively dense cloud of gas was considered as the main mechanism for the deceleration of matter, without which the dust could "stick together" into larger bodies. But the influence of an additional luminary in the system did not allow the smallest fragments of solid matter to form larger objects. Instead, they collided at too high a speed and simply evaporated from the released energy.
The new, detailed model, in turn, after a series of simulations, showed the framework of the conditions under which planets can still form in systems with two luminaries. For this, the protoplanetary disk should have a shape as close to circular as possible. And before the second star begins to make noticeable disturbances in it, planetesimals must have time to "grow" at least up to ten kilometers in diameter.In this case, everything is quite real, and computer modeling demonstrates the successful "birth" of the planetary system.
As an example, in their calculations, Rafikov and Silsby took the parameters of a real-life system - Alpha Centauri. In fact, there are three stars there, but Proxima is small and very far from the large two, so it should not have had a significant effect on the formation of planets. Moreover, exoplanets have been discovered (confirmed) near it, but only candidates have been identified near α Centauri A and B, which are close in size to our Sun. And new modeling confirms the possibility of their existence.