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BROWN dwarfs are hard to spot, but a Japanese PhD student has found the
largest collection ever seen, in the constellation Cygnus about 2000 light years
from Earth. With less than 0.08 times the Sun’s mass, brown dwarfs are too small
and cold to sustain nuclear fusion in their cores, so they grow steadily dimmer.
The Hubble Space Telescope spotted dozens in the Orion Nebula last year, but now
Yumiko Oasa of the University of Tokyo has counted hundreds more in an image
taken by the Subaru Telescope of a gas cloud surrounding a 100,000-year-old
supergiant star.