The Transiting Exoplanet Survey Satellite (TESS) is starting to achieve its goals of “finding planets the size of Earth and orbiting close stars , “ said Paul Hertz, director of the astrophysics division of the NASA. The American space agency announced, Monday, January 6, that its telescope had made it possible to discover a new planet the size of Earth and at a distance neither too close, nor too far from its star for liquid water there either – perhaps – present.
Called “YOU 700 d,” the planet is relatively close to us: a hundred light years away, announced NASA’s Jet Propulsion Laboratory at the Winter Conference of the American Astronomical Society in Honolulu, Hawaii.Article reserved for our subscribers
The system was nearly missed by TESS, but several amateur astronomers, including a high school student by the name of Alton Spencer, discovered an initial classification error, which helped to understand the true nature of the system. The discovery was then confirmed by the Spitzer space telescope.
A few other planets of a similar type have been discovered before, notably by the old Kepler space telescope, but this is the first by TESS, launched in 2018. This satellite fixes part of the sky to detect if objects – planets – are passing in front of stars, which causes a temporary drop in brightness of the star. This allows TESS to infer the presence of a planet, its size, its orbit, etc.
Simulations to predict its composition
The star TOI 700 is small, about 40% of the size and mass of our Sun, with a surface temperature less than half. TESS discovered three planets around this star, named TOI 700 b, c and d. Only the “d” is in the so-called “habitable” area. It is almost the size of the Earth (20% more) and circles its star in 37 days. It receives 86% of the energy supplied by the Sun to the Earth.
One of the simulations, NASA explains, is a planet covered by oceans with “a dense atmosphere dominated by carbon dioxide, similar to what Mars looked like when it was young, scientists supposed . ” A face of this planet always faces its star, as is the case with the Moon with the Earth, a phenomenon called “synchronous rotation”. This face would be constantly covered with clouds, according to this model. Another simulation predicts a version of the Earth without oceans, where the winds would blow from the hidden side towards the lit face.
Multiple astronomers will now observe the planet with other instruments, obtaining new data that may correspond to one of the models predicted by NASA.