Brown Dwarf Atmospheres As The Potentially Most Detectable And Abundant Sites For Life

RockDoctor writes: Yet another provocative paper emerges onto Arxiv from Harvard's Lingam and Loeb. Today they estimate the volume of space occupied by habitable zones (regions where liquid water is stable) in brown dwarf not-quite stars. They find that it could be orders of magnitude greater than the volume in the atmospheres of Earth-size planets. Brown dwarfs are masses of gas which are too small to sustain nuclear fusion (so, they're not stars), but can have a brief period of fusion of deuterium or lithium shortly after formation (so they're not planets; the boundary size is under debate). After this burst of energy, they slowly cool, for billions of years. This leads to a large volume of the star's outer body -- or atmosphere -- with potentially attractive temperature and pressure. If the brown dwarf is orbiting with a larger star, there may be enough light to allow photosynthesis. Supply of chemicals is uncertain, but not impossible.
While this paper is speculative, the prospects for detecting such life by spectroscopy are plausible with observational instruments being designed at the moment. Previous work on abiogenesis and the origin(s) of life has speculated that life could persist in the atmospheres of Venus and Jupiter, using comparable pressure-temperature arguments. In this respect, the proposal is more conventional.

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