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S. K. Leggett (Joint Astronomy Centre Hawaii), X. Fan (Steward Observatory), K. Chiu (Johns Hopkins University), T. R. Geballe (Gemini Observatory), D. A. Golimowski (Johns Hopkins University), Sloan Digital Sky Survey Collaboration
We have obtained near-infrared photometry and spectroscopy for a new sample of spectroscopically-confirmed late L and T dwarfs, expanding the sample presented by Knapp et al. in 2004. This new sample includes two T7.5 dwarfs (classified on the Geballe et al. 2002 scheme), which are the latest types yet found in the Sloan Digital Sky Survey. It also includes three other mid/late T dwarfs, five new early T dwarfs, five new L dwarfs with types later than L7 and eight new L3.5-7 dwarfs. We continue to see a large (about 0.5 mag) range in J-H color for L3 to T1 types, and a similar range in H-K color for all dwarfs later than L3. This spread in color is most likely due to a range in grain sedimentation properties, metallicity and gravity. Dwarfs with unusual colors for their type demonstrate unusual spectral properties which may eventually help disentangle these various parameters.
We have also been following up our sample at longer wavelengths, and have found some correlation between JHK and L'M' colors - for example the reddest known L dwarf is also red in L'-M'. We hope in this paper to present preliminary spectra of SDSS late L and T dwarfs at 5-14 microns, from our Spitzer GO program.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.