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rfmcdonald) wrote2011-02-10 04:30 pm
rfmcdonald) wrote2011-02-10 04:30 pm
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[LINK] "Rogue Planets Could Harbor Life"
Could rogue planets--worlds ejected from their planetary systems--support life? The latest from Lisa Grossman says so.
That second possibility is more dubious, if only because the planet would have to be extraordinarily active. In any case there would likely not be enough energy produced at the vents to sustain macroscopic life forms.
The pair's paper, "The Steppenwolf: A proposal for a habitable planet in interstellar space", is here.
I find the idea fascinating. I did a write-up of such a world, drawing from an earlier model suggesting that a dense atmosphere of molecular hydrogen could retain heat so well as to keep the surface habitable, called Weitwelt for the 2300AD system here. I like difference.
Planet formation models suggest that small planets are regularly flung from their solar systems by close encounters with neighboring gas giants. The giants’ gavitational fields create an interplanetary slingshot effect, sending smaller planets on unstable orbits that quickly leave their star behind.
Prior to ejection, some of those planets could conceivably be like Earth, with continents, oceans and biospheres. A new model suggests that submarine aliens on such a planet could have a chance at survival.
“We originally started with the question, what if you turned off the sun?” said University of Chicago geophysicist Dorian Abbot, co-author of a paper submitted to Astrophysical Journal Letters and pre-published Feb. 5 on arXiv.org.
Along with fellow University of Chicago astrophysicist Eric Switzer, Abbot ran the numbers to see if an ocean could stay liquid without heat from a star. They called their rogue world a Steppenwolf planet, “since any life in this strange habitat would exist like a lone wolf wandering the galactic steppe.”
The pair assumed the planet was between 0.1 and 10 times Earth’s mass, with a similar amount of water and rock. Once the planet fled its warm, nurturing star, the ocean would start to freeze. But leftover heat from the planet’s formation and decaying radioactive elements in the rock could keep the ocean warm beneath a shell of ice. As long as the planet could keep the ice from freezing all the way to the core, the ocean should be safe.
[. . .]
In a slightly more bizarre twist, the Switzer and Abbot imagined the Steppenwolf planet with volcanoes spewing carbon dioxide into the atmosphere. The gas would freeze and fall as snow almost immediately, covering the world with an insulating blanket of dry ice. In that case, planets as small as 0.3 times the mass of Earth could keep a liquid ocean.
That second possibility is more dubious, if only because the planet would have to be extraordinarily active. In any case there would likely not be enough energy produced at the vents to sustain macroscopic life forms.
The pair's paper, "The Steppenwolf: A proposal for a habitable planet in interstellar space", is here.
I find the idea fascinating. I did a write-up of such a world, drawing from an earlier model suggesting that a dense atmosphere of molecular hydrogen could retain heat so well as to keep the surface habitable, called Weitwelt for the 2300AD system here. I like difference.