Meeting the cool neighbors. III. Spectroscopy of northern NLTT stars

We present initial results of an all-sky search for late-type dwarfs within 20 pc of the Sun using the New Luyten Two-Tenths (NLTT) catalog cross-referenced with the Two Micron All Sky Survey (2MASS) database. The results were obtained with low-resolution optical spectroscopic follow-up of candidate nearby stars as a preliminary test of our methodology. M-J, derived using spectral indices, and 2MASS J are used to estimate distances. Out of the 70 objects observed, 28 are identified as previously unrecognized objects within 25 pc of the Sun, and up to 19 of these are within 20 pc. One, LP 647-13, is an M9-type dwarf at 10.5 pc, making it one of the four closest M9 dwarfs currently known. We also discuss the chromospheric activity of the observed dwarfs.