Kelt-9b is an exoplanet located 650 million light-years from Earth and "boiling". In addition, the gas released by this distant world is captured by its star, according to a study published on Monday Nature Astronomy by the Max Planck Institute of Astronomy. Researchers at the Calar Alto Observatory have used the instrument CARMENES to detect the hydrogen that escapes from the planet and show that all this gas is being dragged to his star.

This planet, located outside the system solar, is the hottest still discovered since its temperature rises to 4300 ° C during the day, so many have qualified as "infernal exoplanet" by the conditions that are given. Do not forget that it is hotter than a lot of stars. Now, researchers Fei Yan and Thomas Henning have shown that Kelt-9 the star around which Kelt-9b rotates – which only takes a day and a half to make a full circle from his star -, use his gravity to pull hydrogen and keep it.

To make this discovery, Yan and Henning used a spectrometer, that is, they used an optical instrument that uses light to measure all electromagnetic waves detailed on the physical properties of objects. , gases and even stars. In this case, the instrument calls CARMENES and it is installed in the 3.5-meter telescope of the Observatory of Calar Alto . They discovered that every time the planet was in front of its star, there was a clear line of absorption for hydrogen a region of narrow wavelength where l? Hydrogen-rich atmosphere of the planet absorbed part of the shining light of its star, according to investigators states in a statement

The Flight of hydrogen that undergoes the exoplanet

L & # The extended atmosphere of the exoplanet is "surprisingly large," according to the researchers, since it is more than half the radius of the planet. This extension can be compared, to better understand it, with the tail of a comet . And, depending on the star gravity models that researchers have worked on, it is the maximum size that this extension can have. This size suggests that the exoplanet loses hydrogen a lot of hydrogen: about 100,000 tons per second . Thus, the star boils the atmosphere of the planet and, at the same time, stealing the gas itself.

The way the wavelength of the absorption line changes during the transit of the exoplanet around its star is equivalent to a rare direct detection of the movement of the planet: the displacement of the wavelength it is due to the displacement Doppler which we indicates how fast the observer is getting closer to or away from the planet. "This is a very special type of measurement: this type of direct measurement of planetary motion was only possible for about half a dozen" exoplanets ", explains the researcher Fey Yan, lead author of the article, In a statement

"This planet reminds me of the mythical Icarus, who came too close to Sun and was This exoplanet will not be blocked, but it will certainly lose an essential element and a part of itself: its atmosphere, "comments Thomas Henning director of MPIA and co-author of the. study

Kelt-9b, a "burning Jupiter"

comparing this exoplanet with those there is in the solar system, we can say that it is bigger than Jupiter, with almost three times its mass and twice its diameter. For this reason, scientists cataloged as a "Hot Jupiter" . For its part, the star of Kelt-9b is supermassive, that is to say that it has ten times more mass than our Sun, and its temperature is 9 700 ° C, while our star reached 5500 ° C

by scientists from Ohio State University who were looking for exoplanets by the transit method . This technique makes it possible to measure the brightness of a star since the passage of an exoplanet between the star and the Earth will cause a periodic decrease in the brightness that reaches us, so we can infer indirectly that in this region there is an extrasolar planet.