Space: four questions about Trappist-1, this planetary system that could harbor life 39 light years from Earth

Space: four questions about Trappist-1, this planetary system that could harbor life 39 light years from Earth

The expectation is maximum within the scientific community. The James Webb Telescope began observing the system of seven exoplanets discovered in 2017. This set of planets, similar to Earth and located around a star, could well meet the prerequisites for the possible presence of life forms. Franceinfo explains why, with Trappist-1, researchers have their heads turned to the stars more than ever.

1What is Trappist-1?

In 2017, aan international team led by Belgian researchers from the University of Liège discovers the existence of seven exoplanets, all close in size to Earth. They orbit around Trappist-1, a dwarf star located 39 light-years from our solar system. Why “Trappist”? In homage to the telescope of the same name located in Chile that made this observation… and also in a nod to a Belgian beer.

“Trappist-1 is a red dwarf, when our Sun is a yellow dwarf”, explains to franceinfo Philippe Delorme, a researcher at the Institute of Planetology and Astrophysics of Grenoble (IPAG). It is ten times less massive than our star. red dwarfs they are the smallest and faintest stars; about 80% of the stars are red dwarfs, but none are visible to the naked eye from the Land”details Futura Sciences.

twoWhat are the specificities of these planets?

The seven planets (baptized b, c, d, e, f, g and h) are rocky and not gaseous, like Jupiter or Saturn. These seven planets are very close to their star. “If we were to compare with our solar system, it is as if they were situated in the orbit of Mercury”, illustrates on franceinfo Marc Ollivier, astronomer and director of the Institute for Space Astrophysics in Orsay (Essonne). This means that they revolve around Trappist-1 in a very short time, between a day and a half, for the closest, and 19 days, for the furthest, reports the parisian.

Another feature: this system is less than forty light years from Earth. Knowing that a light year is equal to about 9,500 billion km, Trappist-1 is therefore almost 370,000 billion km from us.

“It is the very close suburb of Earth, when we know that our galaxy, the Milky Way, is 100,000 light-years away.”

Marc Ollivier, astronomer and director of the Institute for Space Astrophysics

in france info

Finally, these planets are aligned, that is, they lower the luminosity of the star when they make their revolution, “which makes them easier to study”adds Philippe Delorme.

3Why does this system excite the scientific community?

Several thousand exoplanetary systems have already been detected in space since the first one in 1995, but this one provokes a particular enthusiasm. “There is a conjunction between the presence of planets in the habitable zone of a star and the observation capacity of James Webb”emphasizes Philippe Delorme. “It is the closest system physically to Earth, with planets that resemble it and are aligned”he adds.

Three of the planets, the e, the f and the g, precise the parisiantherefore, they are in the “living area” of Trappist-1, that is, neither too close nor too far from it, offering adequate temperatures for liquid water to exist on its surface.

“It doesn’t mean there is life, but it does mean it’s not silly to think that.”

Philippe Delorme, researcher at the Institute of Planetology and Astrophysics of Grenoble

in france info

The system “Trappist-1 is uniqueconfirms to AFP Olivia Lim, doctoral student at the University of Montreal. All, or almost all, of the conditions there are favorable for the search for life outside our solar system.”

However, if there is life, it could be very different from what we know on Earth, because the rotation of the planets on themselves and their revolution around Trappist-1 could be synchronous. “As for our Moon, to which we always see the same face, the star would only see one face of the planets, explains Marc Ollivier, It would then be eternal day for this side and eternal night for the other”.

4Why James Webb is changing the game

The Trappist telescope in Chile, if it could find them, could not go much further. James Webb can. “VS”is really the perfect tool to study the Trappist-1 planetary system, a star that emits mainly in the infrared, being James Webb an infrared space telescope”affirms to Parisian Michael Gillon, astronomer from the University of Liège. Thanks to its more sophisticated instruments, it will be able to determine if these planets have an atmosphere and, if so, its composition.

How ? Observing the planets in their transit around the star, that is, in their passage in front of it, from our point of view. With each passage of a planet in front of Trappist-1, James Webb will be able to observe the star’s luminosity drop, but also break its light down, by spectroscopy, just as a rainbow breaks up sunlight into various colors. .

By multiplying the observations, James Webb will be able to identify the possible presence “of biomarker traces, slip philippe delormeor the presence of a gas or a combination of gases that we would detect in an atmosphere, which we cannot explain by anything other than the presence of a life form.” “The presence of methane and oxygen, as on Earth, would be very exciting”concludes the scientist.


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