Water worlds were not all that rare

Scientists believe that water should be an important component of many exoplanets (planets the size 2-4 times larger than the Earth rotating near other stars). If this is confirmed, the approach to the search for life in our galaxy will change. The discovery of exoplanets in 1992 sparked interest in understanding the composition of these planets, because they, among other things, could contain life. Recent data from the space telescope “Kepler” and the mission “Gaia” points to the fact that many of the known planets can 50% composed of water. This is much more than on the Ground (0,02%).

“It was a great surprise to learn that there may be so many water worlds,” says lead researcher Dr. Li Zeng from Harvard University.

How much water on extrasolar planets?

Scientists have found that most of the 4,000 + confirmed exoplanets discovered to date, fall into two size categories: planets with a radius of 1.5 earth and planets with a radius of 2.5 earth.

After analyzing exoplanets based on measurements of radius and mass of the satellite “Gaia”, the scientists developed a model of their internal structure.

“We looked at how weight relates to the radius and developed a model that could explain this relationship”, says Zeng. The model shows that those extrasolar planets that have a radius of about 1.5 earth usually are solid (and have a mass 5 times larger than the earth), and those that have a radius of 2.5 earth (and a mass 10 times greater) — probably water worlds.

“It’s the water, but not like on the Ground,” says Zeng. “It is assumed that the surface temperature is in the range from 200 to 500 degrees Celsius. The surface may be covered with an atmosphere with a predominance of water vapor with liquid flowing under water. Moving deeper, one would expect that this water will turn to ice under high pressure before we reach the hard rocky core. The beauty of this model is that it explains how composition relates to known about these planets facts.”

“Our data show that about 35% of all known exoplanets that more Land needs to be rich in water. These water worlds are probably formed in the same way as the cores of giant planets (Jupiter, Saturn, Uranus, Neptune) that we have found in our own system. Recently launched the TESS mission will find even more of such, with ground-based spectroscopy. The next generation of space telescopes such as James Webb, will characterize the atmosphere of exoplanets. Amazing times to study distant worlds.”

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