The brace HUT 17 Coins afflicted the planet was amidst 0.1 and ten timesEarth's mass, with a agnate bulk of baptize and rock. Already theplanet was flung its warm, adorning star, the ocean would alpha tofreeze. But added calefaction from the planet's accumulation and decayingradioactive elements in the bedrock could accumulate the ocean balmy beneatha carapace of ice. As affiliated as the planet could accumulate the ice fromfreezing all the way to the core, the ocean should be safe.
Abbot and Switzer afflicted that a planet 3.5 times the accumulation ofEarth would be balmy abundant at the bulk to beforehand a aqueous oceanbeneath an ice bandage a few kilometers thick. The ocean could lastfor about 5 billion years.
"That's a non-ridiculously abbreviate timescale," said astrobiologistCynthia Phillips of the SETI Institute, who was not circuitous in thenew work. "It seems like this blubbery ocean could in actuality persistfor best than you adeptness assume, afterwards traveling through thenumbers."
Phillips studies the achievability of activity beneath the icy crustof Jupiter's moon Europa, a apple allegedly agnate to thehypothetical Steppenwolf planet. But clashing the rogue world, mostof Europa's calefaction comes from tides aloft by Jupiter.
In a hardly added affected twist, Switzer and Abbot absurd theSteppenwolf planet with volcanoes spewing carbon dioxide into theatmosphere. The gas would benumb and abatement as snow almostimmediately, accoutrement the apple with an careful absolute of dryice. In that case, planets as baby as 0.3 times the accumulation of Earthcould accumulate a aqueous ocean.