The N2K Consortium. IV. New temperatures and metallicities for more than 100,000 FGK dwarfs

We have created specialized target lists for radial velocity surveys that are biased toward stars that ( 1) possess planets and ( 2) are easiest to observe with current detection techniques. We use a procedure that uniformly estimates fundamental stellar properties of Tycho 2 stars, with errors, using spline functions of broadband photometry and proper motion found in Hipparcos/ Tycho 2 and 2MASS. We provide estimates of T-eff and distance for 2: 4; 106 Tycho 2 stars that lack trigonometric distances. For stars that appear to be FGK dwarfs, we also derive [ Fe/H] and identify unresolved binary systems with mass ratios 1: 25 < M-1/M-2 < 3.0. For FGK dwarfs with photometric error sigma(V) < 0.05; or V < 9, our temperature model gives a 1 sigma error of sigma T +/- 58.7/-65: 9 K and our metallicity model gives a 1 sigma error sigma([Fe/H]) = +0.13/-0.14 dex. The binarity model can be used to remove 70% of doubles with 1.25 < M-1/M-2 < 3.0 from a magnitude-limited sample of dwarfs at a cost of cutting 20% of the sample. Our estimates of distance and spectral type enable us to isolate 354,822 Tycho 2 dwarfs, 321,996 absent from Hipparcos, with giant contamination of 2.6% and 7.2%, respectively. Roughly 100,000 of these stars, not in Hipparcos, have sufficiently low photometric errors to retain 0.13-0.3 dex [Fe/H] accuracy and 80 - 100 K temperature accuracy (1 sigma). Our metallicity estimates have been used to identify targets for N2K, a large-scale radial velocity search for hot jupiters, which has verified the errors presented here. The catalogs that we publish can be used to further large-scale studies of Galactic structure and chemical evolution and to provide potential reference stars for narrow-angle astrometry programs such as the Space Interferometry Mission and large-aperture optical interferometry.