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 Two Micron All Sky Survey. Low-resolution (R$\sim$150) 0.8--2.5 micron spectroscopy obtained with the IRTF SpeX instrument reveal the characteristic H$_2$O and CH$_4$ bands in the spectra of these brown dwarfs. Comparison to spectral standards observed with the same instrument enable us to derive classifications of T3 to T7 for the objects in this sample. Moderate-resolution (R$\sim$1200) near-infrared spectroscopy for a subset of these discoveries reveal K I line strengths consistent with previously observed trends with spectral type. Follow-up imaging observations provide proper motion measurements for these sources, ranging from $
Comment: 27 pages incl. 9 figures and 8 tables, accepted for publication AJ, May 2004; note that findercharts are provided separately as jpg files