Seventy-One New L and T Dwarfs from the Sloan Digital Sky Survey

We present near-infrared observations of 71 newly discovered L and T dwarfs,selected from imaging data of the Sloan Digital Sky Survey (SDSS) using thei-dropout technique. Sixty-five of these dwarfs have been classifiedspectroscopically according to the near-infrared L dwarf classification schemeof Geballe et al. and the unified T dwarf classification scheme of Burgasser etal. The spectral types of these dwarfs range from L3 to T7, and include thelatest types yet found in the SDSS. Six of the newly identified dwarfs areclassified as early- to mid-L dwarfs according to their photometricnear-infrared colors, and two others are classified photometrically as Mdwarfs. We also present new near-infrared spectra for five previously publishedSDSS L and T dwarfs, and one L dwarf and one T dwarf discovered by Burgasser etal. from the Two Micron All Sky Survey. The new SDSS sample includes 27 Tdwarfs and 30 dwarfs with spectral types spanning the complex L-T transition(L7-T3). We continue to see a large (~0.5 mag) spread in J-H for L3 to T1types, and a similar spread in H-K for all dwarfs later than L3. This colordispersion is probably due to a range of grain sedimentation properties,metallicity, and gravity. We also find L and T dwarfs with unusual colors andspectral properties that may eventually help to disentangle these effects.Comment: accepted by AJ, 18 pages, 10 figures, 5 tables, emulateapj layou