Astronomers from NASA and the University of Washington have estimated total internal heating rates and depths to possible subsurface oceans for 17 planets that may be cold ocean planets — low-mass exoplanets with surface temperatures and/or densities that are consistent with icy surfaces and substantial water content. Like the icy moons in our outer Solar System, these planets may be astrobiologically significant worlds that harbor habitable environments beneath their icy surfaces.
Ocean planets are a proposed class of low-density, terrestrial exoplanets with substantial liquid water layers.
They may exist in a variety of climactic states including ice free, partially ice covered, or completely frozen over at their surfaces.
“Our analyses predict that these 17 alien worlds may have ice-covered surfaces but receive enough internal heating from the decay of radioactive elements and tidal forces from their host stars to maintain internal oceans,” said Dr. Lynnae Quick, a researcher at NASA’s Goddard Space Flight Center.
“Thanks to the amount of internal heating they experience, all planets in our study could also exhibit cryovolcanic eruptions in the form of geyser-like plumes.”
Dr. Quick and colleagues considered conditions on 17 confirmed exoplanets that are roughly Earth-sized but less dense, suggesting that they could have substantial amounts of ice and water instead of denser rock.
Although the planets’ exact compositions remain unknown, initial estimates of their surface temperatures from previous studies all indicate that they are much colder than Earth, suggesting that their surfaces could be covered in ice.
The authors improved estimates of each exoplanet’s surface temperature by recalculating using the known surface brightness and other properties of Europa and Enceladus as models.
They also estimated the total internal heating in these exoplanets by using the shape of each exoplanet’s orbit to get the heat generated from tides and…
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