First of all, exoplanet hunters (worlds outside our system) are trying to find planets adapted to life. How to identify potentially suitable? At least you should look for them in the habitable zone.
life may be hiding here
Comparison of the habitability zone of the Kepler-22 planetary system with a sun-like star and the Solar system
The habitable zone (or the Goldilocks zone) refers to a certain distance from the star to the planet (in a particular case) where earthly conditions are observed on the world. That is, the planet receives that amount of heat and radiation, which allow to keep water on the surface in a liquid state.
For example, in the habitable zone is our planet. If the world is closer, then there is a fever, and if further, it is too cold. So the water evaporates or freezes (if it ever was at the facility).
This site is considered the most favorable for the development of life. However, it is important to note that the habitable zone does not guarantee the presence of organisms and developed creatures. Two points should be mentioned here.
First, we still have not determined the exact mechanisms of life formation in the Universe. The habitable zone should guarantee the availability of liquid water, but this is not 100% evidence of the development of living organisms. Secondly, the starting point is the Earth, as this is still the only place where life has been found. Therefore, it is perceived as an ideal model on which other worlds are supposed to be equal. But some believe that life can develop in other forms under more critical conditions, for example, in the methane world and even lava or frost. However, to prove it, you need to find at least one alien species.
Zone of habitability of double stars
Zone of habitability of the planetary system with two stars Kepler-47
If we are talking about the Sun, then it is quite simple for us to define the “part of life”. There is a formula, the main criteria in which is the distance of the planet from the star, as well as the size and level of luminosity of the latter. In our case, everything is simple, because in the solar system there is only one star.
But the bottom line is that about 85% exist at least in pairs. Since several stars appear at once, the habitable zone is able to expand. This is evidenced by the latest astronomical research. Why is it drawn out? It's all about the gravitational interaction of the luminaries.
The findings are based on a new computer model, where they studied how the proximity of stars affects the size of the habitable zone. The analysis has shown that this segment expands or overlaps if the orbital paths of the stars are 5-10 a distant. e. from each other. And in some cases, the planets remained in stable orbits and felt comfortable.
Not so simple
We have already written that the habitable zone does not act as a guarantee of the existence of life on the planet. Most likely, this is just a place to which attention must be paid first of all, but not considered the main criterion. For example, the researchers believed that they broke the jackpot with the TRAPPIST-1 system, in which 3 worlds resided in the Goldilocks zone. However, the activity of their red dwarf proved so strong that it literally sterilized the planets.
In addition, some satellites in more frosty areas still manage to locate liquid water under the ice crust, where life is capable of hiding. This is due to tidal contacts with the planet or the presence of volcanic activity.
As you can see, the researchers are still forced to wander in the dark due to lack of data. It would be much easier to find alien life if we could figure out the exact mechanisms for its formation, even on Earth. Therefore, researchers are working to improve the devices and methods of searching for biological signatures, so as not to miss the potentially valuable worlds.