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

The tension is maximum within the scientific community. The James Webb telescope began observing the system of seven exoplanets discovered in 2017. This set of Earth-like planets located around a star could well fulfill the prerequisites for the possible presence of life forms. Franceinfo explains why scientists with Trappist-1 have their heads in the stars more than ever.

1What is Trappist-1?

In 2017, onediscovers an international team led by Belgian researchers from the University of Liège the existence of seven exoplanets, all of a size close to Earth’s. They orbit Trappist-1, a dwarf star located 39 light-years from our solar system. Why “staircase”? In homage to the telescope of the same name 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, researcher at the Institute of Planetology and Astrophysics in Grenoble (IPAG). It is ten times less massive than our star. red dwarfs “are the smallest and faintest stars; about 80% of stars are red dwarfs, but none are visible to the naked eye from The earth”details Futura Sciences.

2What is special about these planets?

The Seven Planets (christened 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 located in the orbit of Mercury”, illustrates at franceinfo Marc Ollivier, astronomer and director of the Institute of Space Astrophysics in Orsay (Essonne). This means that they orbit Trappist-1 in a very short time, between a day and a half, for the closest, and 19 days, for the farthest, reports The Parisian.

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

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

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

at france info

Finally, these planets are aligned, that is, they lower the brightness of the star as 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 discovered in space since the first one in 1995, but this one arouses particular enthusiasm. “There is a correlation between the presence of planets in a star’s habitable zone and James Webb’s observing capacity”emphasizes Philippe Delorme. “It is the physical system closest to Earth, with planets similar to it and aligned”he adds.

Three of the planets, e, f and g, precise The Parisianis therefore located in “habitable area” of Trappist-1, that is, neither too close nor too far from it, and offer suitable temperatures for liquid water to exist on their surface.

“That doesn’t mean there’s life, but it does mean it’s not stupid to think so.”

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

at france info

The system “Stairway-1 is uniqueconfirms to AFP Olivia Lim, PhD student at the University of Montreal. All, or nearly all, of the conditions favorable to the search for life outside our solar system.”

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

4Why is James Webb changing the game?

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

How ? By observing the planets as they pass around the star, that is, as they pass 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 decrease in the star’s brightness, but also to break down its light, by spectroscopy, just as a rainbow divides sunlight into several colors. .

By multiplying the observations, James Webb will therefore be able to identify the possible presence “of traces of biomarkers, slide Philippe Delormeor the presence of a gas or combination of gases that we would detect in an atmosphere that we cannot explain by anything other than the presence of some form of life.” “The presence of methane and oxygen, as on Earth, would be really exciting”concludes the scientist.

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