A medium-resolution 1.0-2.5 μm spectrum of the brown dwarf Gliese 229B has been obtained using the facility spectrometer CGS4 on the United Kingdom Infrared Telescope. In addition to the broad spectral structure seen in earlier low-resolution observations, the new spectrum reveals a large number of absorption lines, many of which can be identified with water vapor. Water and methane are both shown to be strong absorbers in the near-infrared spectrum of the object. Several spectral features in Gl 229B that are attributable to methane match ones seen in reflection in the giant outer planets and, in particular, Titan.
Bibliographical noteFunding Information:
We thank the many individuals responsible for the excellent construction, maintenance, and operational support of CGS4 and the staff of UKIRT for its support of these observations. We are grateful to R. S. Freedman, D. Schwenke, and D. Saumon for providing us with detailed opacity plots of H2O and CH4 and to T. Owen for permitting us to publish a portion of the spectrum of Titan. We thank the referee, F. Allard, for several helpful comments. We also thank D. Cruikshank, M. Marley, K. Mat-thews, T. Nakajima, and B. Oppenheimer for their assistance. The United Kingdom Infrared Telescope is operated by the Joint Astronomy Centre on behalf of the U.K. Particle Physics and Astronomy Research Council. S. R. K.’s research is supported by Caltech, the US NSF, NASA, and the Packard Foundation. C. E. W. acknowledges support from the US National Science Foundation.
- Infrared: general
- Infrared: lines and bands
- Infrared: stars
- Stars: individual (Gliese 229B)
- Stars: low-mass, brown dwarfs