HARROW: Super Earth exoplantes may host oceans on their surfaces. According to a study from Laura Schaefer at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, MA, and submitted this week at a Seattle meeting of the American Astronomical Society.
Using computer modeling, the study indicated that rocky planets of up to five Earth masses, often called “Super-Earths,” can host oceans on their surfaces for billions of years.
Life could develop in these oceans over long time scales.
“It takes time to develop the chemical processes for life on a global scale, and time for life to change a planet’s atmosphere. So it takes time for life to become detectable,” said study co-author Dimitar Sasselov, also of CfA.
The presence of an ocean on a Super-Earth, especially over a long period of time, could be a better indicator of its habitability than the planet’s temperature and distance from its parent star, Schaefer said. Once these oceans develop, they can exist for billions of years, the study indicated. Planets with two to four times Earth’s mass held onto their oceans for 10 billion years in the computer model.
The largest Super-Earth in the study, with five times the mass of the Earth, took one billion years to form an ocean, but held onto it for billions of years after its formation. Because Super-Earths may be better than Earth itself at hosting oceans over long time periods, scientists searching for extra-terrestrial life should concentrate on the oldest of these worlds, those as much as one billion years older than our planet, Schaefer suggested.
Earth’s oceans, which scientists believe have been present since the planet’s earliest days, undergo recycling, with geological activity transporting water from the crust into the mantle and volcanic activity releasing the water from the mantle back into the oceans.
The computer model confirmed this same recycling process can occur on Super-Earths that experience plate tectonics.
Because liquid water is central to life as we know it, focusing on exoplanets that have long-lived oceans could assist researchers in finding extra-terrestrial life.
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