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Abstract
We present the results of a 0.6 to 4.1 μm spectroscopic survey of a sample of very low-mass stars and brown dwarfs with spectral types ranging from M0 V to T5 V. The survey was conducted with SpeX, a 0.8 to 5.5 μm, medium-resolution spectrograph and imager on the NASA Infrared Telescope Facility. We developed a data reduction package for SpeX called Spextool which performs all the steps necessary to produce fully reduced spectra including preparation of calibration frames, processing and spectral extraction of science frames, wavelength calibration of spectra, and flux calibration of spectra. We have identified the most prominate atomic and molecular absorption features including ∼100 new FeH features, ∼30 new CH4 features, a new band of VO, and ∼80 atomic features. We have also derived the bolometric luminosities and effective temperatures of the dwarfs. Finally, by comparing the dwarf spectra to synthetic spectra computed from model atmospheres we show, for the first time, spectroscopic evidence for the prescence of condenstate clouds in the atmospheres of brown dwarfs.
