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Science 1 December 1995:
Vol. 270. no. 5241, p. 1415
DOI:

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This Week in Science

The nuclear reactions that light up the sun can only occur if a star's mass exceeds 0.08 solar masses; objects smaller than this are called brown dwarfs. Oppenheimer et al. (p. 1478; see the news story by Glanz, p. 1435) report spectroscopic measurements of an unusually low-luminosity brown dwarf, the recently discovered Gl 229B, that has a mass approximately 20 times that of Jupiter. Absorption features in the spectra indicate the presence of methane and water vapor, which implies a surface temperature below 1000 K. The spectra are quite different from those seen in stars and instead bear a greater resemblance to the spectra of Jupiter. The characterization of such objects is necessary to understand whether they could constitute a dominant species in the galaxy.




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