The red dwarf Trappist-1 is orbited by seven rocky planets. For a long time, this large number of planets has made it seem likely that at least one of them might be habitable. Now, in an article in the Astrophysical Journal, astronomers have reported on their results from calculations using previously known data to produce more precise atmospheric models for the seven worlds.
The results have somewhat deflated the hopes of finding planets like Earth in this system. Trappist-1 apparently experienced a very hot youth. This means that all seven worlds probably have a history comparable to that of Venus. Water that might have once existed on these worlds would have evaporated long ago and the planets would now be enveloped by dense, hot atmospheres. There is still some hope for Trappist-1 e, which is located right in the middle of the habitable zone and which the scientists’ model suggests might also be similar to Earth.
In particular, the scientists determined:
- Trappist-1 b, the planet closest to the star, is so hot that not even clouds of sulfuric acid, like on Venus, could form in its atmosphere.
- Trappist-1 c and d receive somewhat more energy from their star than Venus and Earth do from the Sun and might be similar to Venus with a dense, hostile atmosphere.
- Among all seven planets, Trappist-1 e has the greatest likelihood for liquid water on its surface. However, it might have also undergone a formation like that of Venus.
- Trappist-1 f, g, and h, the outer planets, might either be similar to Venus or might be frozen ice worlds, depending on how much water they lost during their formation.