THE NEAR-INFRARED SPECTRUM OF THE BROWN DWARF GLIESE 229B

A medium-resolution 1.0-2.5 mu m spectrum of the brown dwarf Gliese 22 9B has been obtained using the facility spectrometer CGS4 on the Unite d Kingdom Infrared Telescope. In addition to the broad spectral struct ure seen in earlier low-resolution observations, the new spectrum reve als a large number of absorption lines, many of which can be identifie d with water vapor. Water and methane are both shown to be strong abso rbers in the near-infrared spectrum of the object. Several spectral fe atures in G1 229B that are attributable to methane match ones seen in reflection in the giant outer planets and, in particular, Titan.