Tech UPTechnologyTRAPPIST-1 planets may have more water than Earth

TRAPPIST-1 planets may have more water than Earth

Some of the seven exoplanets that orbit the ultracool dwarf star TRAPPIST-1, located almost 40 light years from Earth, could harbor more water than our world , as revealed in a scientific statement by the European Southern Observatory (ESO) .

These exoplanets are basically rocky; However, the density of some of them suggests that up to 5% of their mass could be water –in solid, liquid or gaseous state–, a much higher percentage than in the case of Earth (where only 0.02 % of the mass is water): in fact, that percentage would represent around 250 times more than the sum of the oceans of our planet.

Those exoplanets closest to their star, and therefore hotter, tend to have dense vapor atmospheres; those farthest away, on the other hand, are very likely to have a frozen surface. TRAPPIST-1b, c, d, e, f, g and h are the names these stars have received – named from the closest to the star (b) to the most distant of them (h) -. Of them, the most similar to ours, in terms of size, density and amount of radiation it receives from its star – and which, therefore, arouses more expectation and hopes among scientists – is the fourth (e) , which, Apparently, it would be the rockiest and, in this case, it has a good chance of having water in a liquid state.

It was the TRAPPIST-sur Telescope, installed at ESO’s La Silla Observatory (Chile), which first detected this planetary system in 2016. Subsequent observations, carried out from ground-based telescopes – such as ESO’s Very Large Telescope – or from NASA’s Spitzer Space Telescope, discovered that there were at least seven planets orbiting this faint red star , and that they presented a size similar to that of the Earth.

A much more precise study

Now, a new study carried out by a team of researchers led by scientist Simon Grimm, from the University of Bern (Switzerland), has applied very complex computer modeling methods to the available data and, thanks to this, has been able to to determine the densities of these exoplanets with much more precision than has been done until now.


How have they managed to determine the masses? Grimm explains: “The TRAPPIST-1 planets are so close together that they interfere gravitationally with each other, so when they pass in front of the star, there is a slight change in timing. These changes depend on the masses of the planets, their distances and other orbital parameters. With a computer model we simulate the orbits of the planets until the calculated transits agree with the observed values and from there we derive the planetary masses ”.


These density measurements, combined with models of the compositions of these worlds, suggest quite strongly that they are not sterile rock stars, but appear to contain significant amounts of volatile material , probably water. Eric Agol, also a member of the team, underlined regarding this finding: “For the first time we have a clue that tells us what Earth-sized exoplanets are made of!”


This is one more advance that scientists have made in their goal of deciding whether any of these worlds could be habitable. “The densities, despite being important clues about the composition of the planets, do not say anything about their habitability. However, our study is an important step as we continue to explore whether these planets could support life, ”explains Olivier Brice Demory, co-author of the study from the University of Bern.


Images: ESO / M. Kornmesser

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