TRAPPIST-1, also known as 2MASS J23062928-0502285, is a planetary system located at about 39 light-years of Earth. The main object of this system is a dwarf, ultra-cold, at the limit between red dwarfs and brown dwarfs. This type of star is much colder than the Sun. Around this star orbits at least seven rocky planets. These are planets of a similar or smaller size than the Earth (about three-quarters of the earth’s radius).
Astronomers have discovered around a dwarf and cold star a fascinating system of seven planets similar to Earth, three of which could shelter liquid oceans and therefore the potential for life, says a study published in the journal Nature. According to NASA, this discovery is extraordinarily important in its uniqueness, being the most exoplanets (planets outside our solar system), tellurian (in the same class as the Earth) and at the right distance from the star around which gravitates because on their surface, there may be water in the liquid state. On all seven planets, there may be liquid water if certain atmospheric conditions are met, but the greatest chances are on three of them.
“Now we have a good target to look for the possible presence of life on these exoplanets”, said Amaury Triaud of Cambridge University, co-author of the study.
The seven planets, which have temperatures close to those of the Earth, revolve around a small, light and very cold star, TRAPPIST-1, located in our galaxy, at only 40 light-years from Terra. This discovery may prove to be an important missing piece in the puzzle of spreading life in the Universe.” The answer to the question of whether we are alone is one of the top priorities of science and the discovery of such a large number of such planets at the right distance to their star (for life) is a remarkable step forward towards achieving this goal,” commented Thomas Zurbuchen, associate administrator for the NASA Science Mission Directorate in Washington.
TRAPPIST-1 | The discovery was made by the Spitzer Space Telescope and other terrestrial telescopes
Which is about 40 light-years from Earth (360 trillion kilometres), this planet system is relatively close to us in the Aquarius Constellation. The name of TRAPPIST-1 is the acronym for the name of the Belgian telescope “Transiting Planets and Planetesimals Small Telescope” located in Chile. In May last year, astronomers using TRAPPIST announced the discovery of three planets in this system. The Spitzer orbital telescope, assisted by several terrestrial telescopes, including the European Southern Observatory’s Very Large Telescope, confirmed the existence of these planets and discovered four more.
Using the Spitzer telescope data, the team measured the size of the seven planets and issued the first mass estimates for six of these planets, thus allowing their density to be calculated. The results obtained indicate that all six planets are tellurian. The mass of the seventh planet, furthest from the star, has not yet been estimated, but scientists believe that it is also a tellurian planet, but probably a frozen one.
“The Seven Wonders of the TRAPPIST-1 system are the first Earth-like planets to have been discovered in the orbit of such a star,” according to Michael Gillon, a professor at the University of Liege and study coordinator.”
This system is also the ideal target for studying the atmospheres of potentially habitable planets, the size of the Earth,” he added. Unlike the Sun, the TRAPPIST-1 star classified as an ultra-cold dwarf is so cold that liquid water can exist on the surface of planets orbiting it from very small distances much smaller than would be possible in our solar system. This star has only about 8% of the Sun’s size. All seven planetary orbits in the TRAPPIST-1 system are closer to the host star than Mercury’s orbit to the Sun.
The fact is that these planets are very close to one another. If an astronaut standing on the surface of one of the planets, he could admire the geological characteristics and even the clouds of the planets in the neighbourhood, planets that would appear in the sky higher than the Moon. These planets appear to be in synchronous rotation with their star, just as the Moon is to Earth. This means that a hemisphere of each planet is always directed towards the star, being always day, while the other hemisphere is perpetually submerged in the dark.
The infrared telescope Spitzer watched the TRAPPIST-1 star almost continuously for 500 hours last fall, identifying the planets’ transitions in the system in front of the star. According to Spitzer’s findings, NASA also directed the Hubble Space Telescope to this solar system, observing four planets, 3 of which were in the circumnavigated living area, trying to find out more about the atmospheres of these planets.
“The TRAPPIST-1 system gives us one of the best opportunities in the next decade to study the atmospheres of Earth-like planets,” says Nikole Lewis, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland.
The Kepler Space Telescope, NASA’s principal tool for discovering distant exoplanets, was also heading toward this solar system. Kepler’s data will allow astronomers to learn more about the seven known planets, but also to check whether there are other planets in the orbit of this star. Observations made through the Spitzer, Hubble and Kepler space telescopes will be complemented by what will be done next year by the James Webb Space Telescope. A more sensitive instrument, the space telescope James Webb will be able to detect the chemical signatures of the elements composing the atmospheres of these planets and will also analyze the temperatures and pressure from the surface of these worlds – key factors to determine whether or not they are hospitable to life.
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