Water vapor is found in the atmospheres of small exoplanets – Liberation

Its nickname is as surprising as its discovery: GJ 9827d. The Hubble Space Telescope has observed the smallest known planet outside the solar system to contain water in its atmosphere, the American (NASA) and European (ESA) space agencies announced this Thursday, January 25. “Water is an important discovery on such a small planet”

, said Laura Kreidberg of the Max Planck Institute for Astronomy in Germany, co-director of the research. And to add: “This brings us closer than ever to truly describing Earth-like worlds.”

GJ 9827d, which is about twice the diameter of Earth, is located in the constellation Pisces, 97 light-years away, or more than 900,000 billion km, according to a press release from NASA and ESA. These officials believe that the planet is either a “Mini Neptune” – with a hydrogen-rich and water-filled atmosphere – a hotter version of Jupiter’s moon, Europa, which has twice as much water beneath its crust as Earth.

Wet but very warm

“GJ 9827d may be half water and half rock”Bjorn Benecke of the University of Montreal, who co-led the research, explained. “There will be a lot of water vapor on small piles of rocks”. “Until now, we have not been able to directly detect the atmosphere of such a small planet. And we are slowly getting there. “, he added. For three years, Hubble was able to analyze the wavelengths of colors in the atmosphere of GJ 9827d, when light from the star it orbits filters through its atmosphere, and detects the presence of water molecules.

Even though the planet has a water-rich atmosphere, its 425°C temperature makes it uninhabitable. The discovery, however, paves the way for other studies of GJ 9827d and similar planets, particularly by the James Webb Space Telescope, which can use its high-resolution infrared images to detect other atmospheric molecules such as carbon dioxide and carbon dioxide. . Methane.