THE NEAR-INFRARED SPECTRUM OF THE SUSPECTED BROWN DWARF BINARY-SYSTEM GLIESE-473

We discuss near-infrared spectroscopic observations of the low-mass binary system Gliese 473AB (Wolf 424), the components of which may have substellar masses [Heintz, A&A, 217, 145 (1989)]. The composite spectrum of GL473AB in the wavelength range 2.0-2.5-mu-m is compared with those of the main-sequence binary systems Gliese 65AB (UV Ceti) and Gliese 866AB. The strengths of CO and H2O absorption in the spectra of all three systems are found to be similar, although subtle differences may be present among atomic features. If the components of GL473AB had masses as low as that predicted by Heintz (1989) then their surface gravities would be more than a factor of two lower than those of main-sequence stars of comparable brightness, and the near-infrared spectroscopic data suggest that this appears not to be the case. More specifically, although the current data cannot unambiguously rule out substellar masses for the components of GL473AB, it suggests that their masses must be greater than approximately 0.06M.. Finally, we note that if the components of GL473AB have substellar masses then they must be very young, with an age of only approximately 100 million years. The possibility of finding stars of this age in the solar neighborhood is briefly discussed.