Thursday, November 8, 2012

Super-Earth Discovered In Stars' Habitable Zone

Just to play devil's advocate here.

Let's assume that we have a neptune sized gas giant going through its daily grind around its parent star, and that it has a magnetosphere. (Only 1 in 50 red dwarf systems have a jupiter mass object in orbit, but 1 in 3 has a neptune mass object.)

That close to its parent star, it would collect a tremendous amount of "cold" stellar plasma. (our little dirtball collects enough to create the van allen radiation belts. A neptune sized object would create a radiation torus MUCH larger.) This would inflate the magnetosphere to gargantuan proportions. This means that a great many of the proposed moons orbiting the gas giant would still retain thick atmospheres, unless other cosmic forces were actively at work to strip them. (like I think Enceladus's interaction with Saturn's magnetosphere...) Under such conditions, a rocky body like jupiter's moon Titan, which has a thick nitrogen and hydrocarbon atmosphere would be heated by both tidal heating, and be within the habitable zone. It would have an abundance of volcanic activity, and would get sufficient light that it could theoretically develop a biosphere.

If you throw into the mix all the red dwarf stars in our local star cluster, and the shockingly large number of detected gas giant planets we have detected so far in "inner" solar system orbits, a solution to the problem of potentially habitable bodies in red dwarf systems becoming tide-locked is provided by moons orbiting habitable zone gas giants. Such systems would be well protected from meteor impacts, as the gas giant would sweep the vast majority of objects out of the orbital path of the pair. The gas giant would keep the rotation and orbital period of the moon on a nice even keel, and would provide a strong magnetosphere.

If I were looking for a place to build a colony that could last a VERY VERY long time, I would look for goldilocks gas giants with habitable moons around red dwarf stars. The only niggly problem is the statistical scarcity of light elements like hydrogen in these systems. (M type stars are very rich in metals, but light on hydrogen and helium compared to more larger and more luminous stars. Any moons orbiting such gas giants are more likely to have an excessive amount of crustal oxygen than in other types of system, as metal oxide spectral lines are a mainstay feature of M type stars.) This might be resolvable if the system is "Absurdly old", as the high concentration of heavy elements would suggest a high level of radiological isotopes in the mineral composition of the planetary and satellite objects of such systems. This means that radiologically produced hydrogen from fission reactions over time could provide the missing hydrogen. M type star systems are quite capable of persisting to such advanced cosmic ages.

I would be very interested in the prospect of habitable satellites of massive objects in red dwarf systems, and think that planets like ours get too much attention in the search for habitable bodies.

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/2PkmL8M0rC4/super-earth-discovered-in-stars-habitable-zone

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