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Published November 30, 1995 | public
Journal Article

Discovery of a cool brown dwarf

Abstract

Brown dwarfs are star-like objects with masses less than 0.08 times that of the Sun, which are unable to sustain hydrogen fusion in their interiors. They are very hard to detect, as most of the energy of gravitational contraction is radiated away within ~10^8 yr, leaving only a very low residual luminosity. Accordingly, almost all searches for brown dwarfs have been directed towards clusters of young stars—a strategy that has recently proved successful. But there are only modest observable differences between young brown dwarfs and very low-mass stars, making it difficult to identify the former without appealing to sophisticated models. Older brown dwarfs should have a more distinctive appearance, and if they are companions to nearby stars, their luminosity can be determined unambiguously. Here we report the discovery of a probable companion to the nearby star G1229, with no more than one-tenth the luminosity of the least luminous hydrogen-burning star. We conclude that the companion, G1229B, is a brown dwarf with a temperature of less than 1,200 K, and a mass ~20–50 times that of Jupiter.

Additional Information

© 1995 Nature Publishing Group. Received 25 September; accepted 13 November 1995. We thank P. Goldreich, E. S. Phinney, I. N. Reid and M. van Kerkwijk for discussions. Some of the observations were conducted at the Palomar 60-inch telescope. which is jointly owned by the California Institute of Technology and the Carnegie Institution of Washington. At Caltech, this research was initiated from a seed grant from the Flintridge Foundation. S.R.K. is deeply indebted to the Foundation. The construction of the AOC was funded by the Seaver Institute. S.T.D. is grateful for their generous support. Our current activities are supported by the Packard Foundation, the US NSF and NASA. Infrared astronomy at Palomar is supported by the US NSF. B.R.O. is supported by an NSF graduate Fellowship. D.A.G. and S.T.D. thank the Center for Astrophysical Sciences at JHU for its support of this work.

Additional details

Created:
September 14, 2023
Modified:
October 23, 2023