ASTRONOMERS have glimpsed a new type of celestial object鈥攕maller and
cooler than most brown dwarfs but larger than giant planets.
Two of these 鈥渕ethane dwarfs鈥� were found using data from the Sloan Digital
Sky Survey (SDSS), which systematically maps the night sky. With a surface
temperature of 900 K, the first of the objects is 鈥減robably too cool to be
called a star鈥�, says Xaiohui Fan of Princeton University, New Jersey, at a
meeting of the American Astronomical Society in Chicago last week.
A second, nearly identical object was found by astronomers at Johns Hopkins
University in Baltimore, also using the SDSS. The objects have masses between 10
and 70 times that of Jupiter and have atmospheres rich in methane.
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