Study finds that many exoplanets can be water rich



A team of scientists has discovered that several exoplanets between two and four times the size of the earth probably contain a considerable amount of water, a discovery that can have consequences for the search for life in the galaxy.

The researchers have discovered that several of the well-known exoplanets can contain up to 50 percent water after analyzing data from the Kepler Space Telescope and the Gaia mission.

"It was a huge surprise to realize that there must be so many water worlds," said lead researcher Li Zeng, PhD, from the University of Harvard, in a statement.

Previously, scientists distributed the 4,000 confirmed or candidate exoplanets in two size-class planets with a planetary radius of about 1.5 the size of the earth or planets with a planetary radius of about 2.5 times that of the earth.

In the new study, the scientists further analyzed the exoplanets with mass measurements and radius measurements to develop a model of their internal structure that indicates that the planets of about 1.5 times the size of the earth tend to be rocky planets, while the other planets could be water the world.

"We looked at how mass relates to radius, and developed a model that could explain the relationship," Zeng said. "This is water, but not as usual here on earth, and their surface temperature is expected to be in the range of 200 to 500 degrees Celsius.

"Their surface can be shrouded in an atmosphere dominated by water vapor, with a liquid layer of water underneath.When we go deeper, you would expect this water to transform into high-pressure ice before we reach the solid rocky core.The beauty of the model is that it explains how composition relates to the known facts about these planets. "

The new data indicate that about 35 percent of the known exoplanets larger than the earth are water rich.

"These water worlds are probably shaped in the same way as the giant planetary cores [Jupiter, Saturn, Uranus and Neptune] that we find in our own solar system, "Zeng said." The newly launched TESS mission will find much more, using ground-based spectroscopic follow-up.

"The next generation space telescope, the James Webb Space Telescope, will hopefully characterize the atmosphere of some of them, an exciting time for those interested in these remote worlds."

The researchers presented their findings during the Goldschmidt Conference in Boston from 12 to 17 August.


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