Brown Dwarfs Sparser than Expected

Nobody has been anticipating the results from WISE — the Wide-field Infrared Survey Explorer — any more than I have. Speculations about the number of brown dwarfs in the galaxy have been all over the map, with some suggesting they might be as plentiful as M-dwarfs, which make up perhaps 80 percent of the stellar population. But the latest results from our infrared scan of the sky argue a much different result: Brown dwarfs turn out to be considerably more rare than stars, with an initial tally of the WISE data showing just one brown dwarf for every six stars.
Thus Davy Kirkpatrick, a member of the WISE science team at NASA’s Infrared Processing and Analysis Center at Caltech:
“This is a really illuminating result. Now that we’re finally seeing the solar neighborhood with keener, infrared vision, the little guys aren’t as prevalent as we once thought.”
Ouch. The nice thing about a sky full of undiscovered brown dwarfs was that it might serve up interstellar destinations closer than the Alpha Centauri stars. None has been discovered yet, and we’ll apparently have to travel a lot farther to move between average-spaced brown dwarfs than we once thought. Not that these ...