The exoplanet closest to our solar system discovered to date could be covered by an ocean, shows a scenario established by French scientists. Explanations.
Scientists have announced the discovery of the small Proxima B last August. This earth-like rocky planet is orbiting the Proxima Centaur star, which is 4.2 light years from our solar system.
It is at a distance of 0.05 astronomical unit from its star. It is 20 times closer than the Earth is from the Sun. His star, a red dwarf, is much less brilliant than ours. Proxima B is therefore well in the habitable zone, and its temperature would allow the presence of liquid water on its surface, an essential condition for the appearance of life.
French astrophysicists from the University of Aix-Marseille have drawn up two scenarios using simulations:
- If it is small: the researchers estimated that its minimum radius would approach 5990 km. It would be in this case very dense. Its core would be metallic and very big. It alone would make up two-thirds of the planet. The rest would consist of a rocky mantle and perhaps even a little water. This does not exclude the presence of water on the surface of the planet, as on Earth, where the body of water does not exceed 0.05% of the mass of the planet. Proxima B would then look a bit like Mercury, the planet in our solar system closest to our Sun.
- If it is larger: with a maximum radius of 8920 km, it would be composed of 50% rocks surrounded by 50% water. All this water would form an immense ocean, with a depth of 200 km, which would cover the entire surface of the planet. In both cases, a thin gaseous atmosphere would encompass the planet, as on Earth, making Proxima B potentially habitable.
Because of its proximity, the celestial object could become the first planet outside our solar system to receive a probe visit.
The details of this work will be published shortly in The Astrophysical Journal Letters .