Scientists have found evidence that the two exoplanets orbiting the red dwarf are “water worlds,” planets where water makes up most of their volume. Reported by the University of Montreal.
Both planets are located in the Kepler-138 system, 218 light-years away in the constellation Lyra. They were studied using the Hubble and Spitzer orbiting telescopes.
“We used to think that planets slightly larger than Earth were big balls of metal and stone, like magnified versions of our planet, and that’s why we called them super-Earths,” the scientists explain. “However, we have now shown that these two planets, Kepler-138c and d, are completely different: most of their volume is likely water. For the first time, we observe planets that can be safely identified as water worlds, the existence of which astronomers have long predicted.”
Water was not directly detected, but by comparing the sizes and masses of planets with models, scientists concluded that a significant part of their volume – up to half – must consist of materials lighter than stone but heavier than hydrogen or helium. , forming gas giants. . The most common remaining material is water.
Planets c and d have more than three times the volume of the Earth and twice the mass of the Earth. Scientists often compare them to the enlarged icy moons of Saturn and Jupiter, such as Europa and Enceladus. But astronomers have calculated that the temperatures on these planets are above the boiling point of water, so they are unlikely to have classical oceans. Most likely, the atmospheres of the planets consist of very dense superheated vapor that, below a certain height, turns into water or supercritical fluid.