"Super-Earths" could have atmospheres more similar to the Blue Planet than researchers previously believed.
Massive planets called "super-Earths" are common in our galaxy, the Milky Way. Now, though, scientists have found that these planets are far more likely to have an Earth-like climate than previously thought. Artist's rendition of a transit of GJ 1214 b in blue light. The blue sphere represents the host star GJ 1214, and the black ball in front of it on the right is GJ 1214 b. (Photo : NAOJ)
These planets are common in the Milky Way, and new research suggests they may contain vast continents surrounded by liquid oceans, a Northwestern University news release reported.
Past theories have suggested super-Earths' surfaces were completely submerged in liquid; new research challenged that idea, claiming tectonically-active super-Earths would store liquid in their mantle leaving continents exposed. This type of composition could allow the planets to have an Earth-like "stable" environment.
"Are the surfaces of super-Earths totally dry or covered in water?" Nicolas B. Cowan, a postdoctoral fellow at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics said. "We tackled this question by applying known geophysics to astronomy. Super-Earths are expected to have deep oceans that will overflow their basins and inundate the entire surface, but we show this logic to be flawed," he said. "Terrestrial planets have significant amounts of water in their interior. Super-Earths are likely to have shallow oceans to go along with their shallow ocean basins."
The researchers believe plate tectonics cause liquid to cycle between the super-Earth's surface and its mantle. Their model focuses on factors such as seafloor pressure and high gravity. They believe that larger super-Earths have higher pressure in both fields.
"We can put 80 times more water on a super-Earth and still have its surface look like Earth," Cowan said. "These massive planets have enormous seafloor pressure, and this force pushes water into the mantle."
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