Exoplanet hunters discovered the existence of two planets that have a water content like Earth. Is it habitable?
Using NASA's Hubble Space Telescope and the retired Spitzer Space Telescope, scientists identified two apparently submerged exoplanets that are one of the pillars of life.
Located in a star system about 218 light years away, the blue planets, named Kepler-138 c and Kepler-138 d, orbit a faint red dwarf star.
Quoted from CNET, Kepler-138 c and Kepler-138 d are about one and a half times the size of Earth and have a mass roughly twice that of our planet.
"We previously thought that planets slightly larger than Earth were metal filled planets or giant chunks of rock, like enlarged versions of Earth, and that's why we called them super Earths," said Björn Benneke, professor at the University of Montreal. and one of the authors of this paper.
In fact, NASA's online Exoplanet catalog still refers to Kepler d, for example, as a "potentially rocky" world. However, said Benneke, their research had shown that the two planets had very different properties.
"A large part of its entire volume is probably made up of water," Benneke said.
Overall, it marks the first time that scientists have confidently identified a found exoplanet as a water world, which Benneke says is the type of planet astronomers have theorized to have existed for a long time, but have yet to prove with great certainty.
Before we go any further, the main thing to keep in mind is that these so-called watery planets didn't always have oceans as one might think.
"The temperatures in the atmospheres of Kepler-138c and Kepler-138d are likely to be above the boiling point of water, and we predict there are thick, dense atmospheres made of vapor on these planets," said Caroline Piaulet, team leader and Ph.D. student at the University of Montreal.
"Only under the atmosphere, that vapor has the potential to become liquid water at high pressure, or even water in another phase that occurs at high pressure, which is called a supercritical fluid," he continued.
Researchers think the Kepler twins are more like a larger version of Europa or Enceladus. To note, Europa and Enceladus are water-rich moons currently orbiting Jupiter and Saturn.
"Instead of an ice surface, Kepler-138 c and d will host a large shroud of water vapor," said Piaulet.
Technically, both of the exoplanets studied have been discovered by NASA's Kepler Space Telescope in the past (hence their name), but it's only now that scientists feel they have confirmation of the planet's composition.
Although they have confirmed Kepler-138 b, which is also in the red dwarf system Kepler 138, is a terrestrial planet with a mass of about 0.0066 Earth masses, they need further observations for c and d.
"As our instruments and techniques become sensitive enough to find and study planets far from their stars, we may start to find more water worlds like Kepler-138 c and d," said Benneke.
Plus, an added bonus to these observations is the discovery of a new baby planet Kepler 138 which will probably be named Kepler-138 e.
Piaulet and his team were surprised to see the presence of a fourth planet in the system that is smaller and farther from its star than the other three. But perhaps most interestingly, Kepler-138 e appears to be in the habitable zone.