Scientists from the University of Washington (USA) presented an updated climate model for the seven planets of the star TRAPPIST-1, which will help astronomers study the extrasolar worlds more efficiently and use the resources of future generations of telescopes more productively.

This is a whole sequence of planets that can give us an idea of ​​the evolution of worlds, in particular, revolving around stars, which are very different from ours.

-Andrew Linkowski, lead author of the study

The team discovered that due to the extremely hot and bright early phase of the TRAPPIST-1 star, all seven of its planets may have evolved like Venus, initially having oceans that evaporated and left a dense, unfit atmosphere. However, one of them, TRAPPIST-1 e, may still contain an ocean of the Earth type, and deserves further scrutiny.

The relatively cold red dwarf TRAPPIST-1 is located 39 light-years from Earth. Compared to the parameters of the Sun, the star’s mass is about 9 percent, and the radius is about 12 percent. All seven TRAPPIST-1 planets are similar in size to the Earth, and three of them (the planets designated e, f, and g) are in the habitable zone in which they can have liquid water on the surface. TRAPPIST-1 d intersects the inner edge of the habitable zone, and TRAPPIST-1 h rotates beyond its outer edge.

By combining Earth climate modeling with a photochemical model, the researchers simulated the state of the environment for each of the TRAPPIST-1 worlds. The results showed that:

  • TRAPPIST-1 b, the closest planet to the star, is too hot even for the formation of sulfuric acid clouds, like on Venus;
  • TRAPPIST-1 c and d receive a little more energy from their star than Venus and the Earth from the Sun, and may look like Venus with a dense, uninhabitable atmosphere;
  • TRAPPIST-1 e is most likely to have liquid water on the surface and would be an excellent choice for further searching for signs of life;
  • the outer planets TRAPPIST-1 f, g and h can be similar to Venus or be frozen, depending on how much water is left on them during the evolutionary period.

What forms of life can exist in the TRAPPIST-1 system?

Astronomers believe that in fact any or all of the planets of the TRAPPIST-1 system may be similar to Venus. When water evaporates from the surface of the planet, ultraviolet light from a star breaks its molecules, releasing hydrogen, which is the lightest element and can overcome the gravity of the planet. As a result, the formation of a thick oxygen atmosphere is possible, but not the one that we associate with life, but completely different from everything familiar to us.

The processes that form the evolution of a planet of the terrestrial type are crucial for its habitability, as well as for our ability to determine the signs of such a life. The study suggests that we will soon learn to distinguish the potential signatures of these processes in foreign worlds.

-study co-author Victoria Meadow, a professor of astronomy and director of the astrobiology program

The climate model has become the key to the habitability of the multi-planet system TRAPPIST-1
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