They discover two twin exoplanets that may be made of water

The discovery of new details of the exoplanets of Kepler-138 was made thanks to observations from the Hubble and Spitzer telescopes.


Scientists at the University of Montreal have found evidence for the existence of two exoplanets composed largely of their evidence by water .

These stars are located in the Kepler-138 planetary system , 219 light years away, in the constellation Lyra, and they do not resemble any planet in our solar system.

The investigation

The study was led by Caroline Piaulet of the Trottier Institute for Exoplanet Research at the University of Montreal. It was published in the journal Nature Astronomy .

The group discovered new information about the exoplanets Kepler-138 c and Kepler-138 d thanks to observations from the Hubble and Spitzer telescopes. They were initially discovered by the Kepler telescope, which also had Kepler-138 b on its radar.

The study points out that, by comparing the masses and sizes of the planets with established models, it can be concluded that a significant fraction, almost 50%, could be composed of water.

This approximation is not conclusive since these materials must be lighter than rock, but heavier than hydrogen or helium. The most common of these possible cases is water .

“We used to think that planets that were slightly larger than Earth were big balls of metal and rock, like scale versions of Earth, and that’s why we called them super-Earths,” explained Björn Benneke, study co-author and professor in astrophysics at the University of Montreal. “However, we have now shown that these two planets, Kepler-138 cyd , are very different in nature and that a large fraction of their total volume is likely to be made up of water . So far, it is the best evidence for water worlds , a class of planets whose existence has been theoretically postulated by astronomers for a long time.”

Both planets have a volume nearly three times that of Earth and more than twice its mass.

You have to keep your emotions

The researchers point out that planets, if they had water , might not have oceans directly on their surfaces.

“The temperature in the atmosphere of Kepler-138 d is probably above the boiling point of water , and we expect to see a thick, dense atmosphere made of steam on this planet. Only under that vaporous atmosphere could there be liquid water at high pressure, or even water in another phase that occurs at high pressures, called supercritical fluid,” Piaulet said.

To these two worlds is added a third discovered in the current study, Kepler-138 e, which is within the habitable zone, which would allow the existence of liquid water . But few details are known about it, since it seems not to transit in front of its star.