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As part of a comprehensive effort to characterize the nearest stars, theCHIRON echelle spectrograph on the CTIO/SMARTS 1.5m telescope is being used toacquire high resolution (R = 80000) spectra of K dwarfs within 50 parsecs. Thispaper provides spectral details about 35 K dwarfs from five benchmark sets withestimated ages spanning 20 Myr -- 5.7 Gyr. Four spectral age and activityindicators are tested, three of which aligned with the estimated ages of thebenchmark groups -- the Na I doublet (5889.95 $\r{A}$ and 5895.92 $\r{A}$), theH$\alpha$ line (6562.8 $\r{A}$), and the Li I resonance line (6707.8 $\r{A}$).The benchmark stars are then used to evaluate seven field K dwarfs exhibitingvariable radial velocities for which initial CHIRON data did not show obviouscompanions. Two of these stars are estimated to be younger than 700 Myr, whileone exhibits stellar activity unusual for older K dwarf field stars and ispossibly young. The four remaining stars turn out to be spectroscopic binaries,two of which are being reported here for the first time with orbital periodsfound using CHIRON data. Spectral analysis of the combined sample of 42benchmark and variable radial velocity stars indicates temperatures rangingfrom 3900--5300 K and metallicities from $-$0.4 $<$ [Fe/H] $<$ $+$0.2. We alsodetermine $log g$ = 4.5--4.7 for main sequence K dwarfs. Ultimately, this studywill target several thousand of the nearest K dwarfs, and provide results thatwill serve present and future studies of stellar astrophysics and exoplanethabitability.

The Solar Neighborhood L: Spectroscopic Discovery of K Dwarfs Younger Than 1 Gyr and New Binaries within 30 pc