The TRAPPIST-1 system, some 40 light-years from Earth, is dominated by an ultracool dwarf star around which three Earth-sized planets orbit . Since their discovery, these worlds have aroused the interest of astronomers, not only because objects of this type have never before been detected around such a small star – this would be somewhat larger than Jupiter, and its brightness would hardly represent a 0, 05% that of the Sun – but because, it seems, at least one, if not all, would be in the habitable zone of its galactic neighborhood. In this region, the necessary conditions would exist for water to exist in a liquid state on its surface, and perhaps life as we know it.
Now, the same team of researchers that announced the discovery of these exoplanets has revealed that the two closest to their star are rocky worlds, such as Earth, Venus or Mars, and that like these they have more compact atmospheres than if they were planets gaseous , like Jupiter or Saturn. In an article published in the journal Nature , these scientists point out, however, that more studies are needed to determine the structure and composition of its gas envelope: it may be made up of water vapor and lack clouds, or it may be as dense as that of Venus, composed mostly of carbon dioxide; it could even look like Earth’s.
The astronomers, coordinated by Julien de Wit, from the Department of Planetary, Atmospheric and Earth Sciences at the Massachusetts Institute of Technology, used the Hubble Space Telescope to observe the double transit of both exoplanets, the moment when the two passed simultaneously in front of your star. This is a rare phenomenon, and in fact scientists realized that it was going to take place only two weeks before it happened . In any case, it allowed them to perform a preliminary spectroscopic analysis of their atmospheres.
Image: NASA / ESA / STScI
