14 Jul 10
3 edits
Originally posted by r99pawn77"The 14 objects found by Spitzer are hundreds of light-years away -- too far away and faint for ground-based telescopes to see and confirm with a method called spectroscopy. But their presence implies that there are a hundred or more within only 25 light-years of our sun.
Coolest Stars Come out of the Dark: Spitzer Spies Frigid Brown Dwarfs
http://www.sciencedaily.com/releases/2010/06/100629112152.htm
Because WISE is looking everywhere, it will find these missing orbs, which will be close enough to confirm with spectroscopy. It's possible that WISE will even find more brown dwarfs within 25-light years of the sun than the number of stars known to exist in this space."
Not sure how they figure that one. If they have found 14 of these things 'hundreds' of light years away, wouldn't that say, if they are not clustered but randomly spaced, say the 14 were found at 250 ly out, then at 25 ly, it should be the cube root of the ratio, in this case 14/ (250^3/25^3), it looks to me like there wouldn't be any within 25 ly.
Why would they say there would be seven times MORE in such a small volume of space?
For instance, if you compute the difference between 250 light years ^3 and 50 Light years ^3, you find the larger volume to be 75 times greater so it would be 14/75 or less than one, and the difference in volume of 250 ly^ V 25 ly^3 would be 1000:1 so how could there be 'hundreds' in that smaller volume?