We present the first mid-infrared spectra of brown dwarfs, together with
observations of a low-mass star. Our targets are the M3.5 dwarf GJ 1001A, the
L8 dwarf DENIS-P J0255-4700, and the T1/T6 binary system epsilon Indi Ba/Bb. As
expected, the mid-infrared spectral morphology of these objects changes rapidly
with spectral class due to the changes in atmospheric chemistry resulting from
their differing effective temperatures and atmospheric structures. By taking
advantage of the unprecedented sensitivity of the Infrared Spectrograph on the
Spitzer Space Telescope we have detected the 7.8 micron methane and 10 micron
ammonia bands for the first time in brown dwarf spectra.Comment: 4 pages, 2 figure