Scientists say there may be life on icy exo-Earths outside the habitable zone

(ORDO NEWS) — Under the icy crust of cold exo-Earths, there may be liquid water and life, even if they are outside the traditional habitable zone.

Astrobiologists traditionally distinguish a habitable zone – a set of orbits around a star, being on which the planet should be able to support life.

Since the key parameter for life is the presence of liquid water, the planet must be warm enough for water to melt, but not hot enough for it to evaporate.

This interval is quite narrow and many Earth-like planets are in the freezing zone.

Scientists from Rutgers University conducted calculations and came to the conclusion that such planets can still have liquid water.

The source of heat for it is not the star, but the core, and in this case atmospheric pressure becomes unimportant.

In addition, melting can occur due to pressure and friction of ice against each other and against the rock bottom.

The authors note that even a weak geothermal flow, like that formed on the Moon, can provide enough heat.

Water in such oceans interacts with rocks and exchanges chemicals with them, and is also protected from radiation. Both of these factors are important for life.

The situation is complicated on super-Earths, whose gravity is much greater than Earth’s.

Water ice can form 18 different modifications when subjected to higher pressure and different temperatures, and different modifications of ice can create layers that hold water together.

This effect is especially important for red dwarf systems, whose classical habitable zone is too close to the star.

Because of this, the planet is subject to tidal capture and excessive exposure to the solar wind, which negatively affects habitability.

Therefore, if life is possible outside this zone, this significantly expands the search field for astronomers.

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