The 2MASS Wide-Field T Dwarf Search. III. Seven New T Dwarfs and Other Cool Dwarf Discoveries We present the discovery of seven new T dwarfs identified in the TwoMicron All Sky Survey. Low-resolution (R~150) 0.8-2.5 μm spectroscopyobtained with the Infrared Telescope Facility (IRTF) SpeX instrumentreveals the characteristic H2O and CH4 bands inthe spectra of these brown dwarfs. Comparison with spectral standardsobserved with the same instrument enables us to derive classificationsof T3 to T7 for the objects in this sample. Moderate-resolution (R~1200)near-infrared spectroscopy for a subset of these discoveries reveal K Iline strengths consistent with previously observed trends with spectraltype. Follow-up imaging observations provide proper-motion measurementsfor these sources, ranging from less than 0.1" to 1.55" yr-1.One object, 2MASS 0034+0523, has a spectrophotometric distance placingit within 10 pc of the Sun. This source also exhibits a depressed K-bandpeak reminiscent of the peculiar T dwarf 2MASS 0937+2931 and may be ametal-poor or old, high-mass brown dwarf. We also present low-resolutionSpeX data for a set of M- and L-type dwarf, subdwarf, and giantcomparison stars used to classify 59 additional candidates identified asbackground stars. These are primarily M5-M8.5 dwarfs, many exhibiting HI Paγ, but include three candidate ultracool M subdwarfs and onepossible early-type L subdwarf.
