Scientists have reported that “super-Earths” in our galaxy have more chances of having climate similar to Earth. These chances are more than our previous expectations.
Before this research, it was commonly thought that super-Earths are unlike Earth. However, after this research, we know that super-Earths would be “waterworlds” having most of the water in the mantle – the part of the Earth or another planet that lies between the crust and core, and constitute most of the volume and mass of the planet – and would have oceans and exposed continents.
“Are the surfaces of super-Earths totally dry or covered in water?” Cowan 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.”
Water constantly moves back and forth between the ocean and the rocky mantle due to plate tectonics. Seafloor pressure is the controlling factor in the division of water between ocean and mantle.
“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.”
“We conclude that a tectonically active terrestrial planet of any mass can maintain exposed continents if its water mass fraction is less than ~0.2%, dramatically increasing the odds that super-Earths are habitable,” Researchers noted.
Cowan presented the findings at a press conference, “Windows on Other Worlds,” held Jan. 7 at the 223rd meeting of the American Astronomical Society (AAS) annual meeting in Washington, D.C.
Massive Exoplanets May Be More Earth-Like Than Thought: ‘Super-Earths’ Likely to Have Oceans, Continents – Northwestern University (http://goo.gl/9MxE9U)
Nicolas B. Cowan et al. (2014). Water Cycling Between Ocean and Mantle: Super-Earths Need Not Be Waterworlds Astrophysical Journal DOI: 10.1088/0004-637X/781/1/27