In a new study, astronomer Marit Mollus from the University of Zurich in Switzerland has proved that a good, dense atmosphere of hydrogen and helium can maintain temperatures and conditions suitable for life.
It is quite possible that exoplanets, for example, super-earths, can retain their pristine atmosphere much longer than Earth.
In their atmospheres, a greenhouse effect can occur — very similar to the Earth’s atmosphere today. Therefore, the authors wanted to find out whether such an atmosphere could create the necessary conditions for the preservation of liquid water.
To find out, the team used exoplanet simulations. They took scenarios when the planets had different cores, different atmospheres and the orbital distances from the stars changed.
As a result, it turned out that exoplanets with a dense primary atmosphere can indeed retain heat and maintain liquid water for 10 billion years.
But there are other important factors. To avoid intense stellar radiation that can destroy the primary atmosphere, the exoplanet must be at a considerable distance from the star — about twice as much as the Earth is from the Sun. As for the Solar System, it is so far from the Sun that any water on the surface of the planet is likely to freeze.
But the stars are not the only source of heat. Some planets, in particular the Earth, can produce their own heat. For example, due to geothermal processes or from radioactive elements that emit heat during decay.
Thus, according to the researchers, if an exoplanet at such a distance from its host star had a primary atmosphere and a sufficient amount of internal heat, then water would remain on it and, possibly, life would form.