Hertzsprung-Russell diagram of the single and SB1 sources with known parallaxes. The symbols are color coded by log g. The evolutionary tracks of Girardi et al. (2000) are shown as solid lines with the labels representing their masses. The zero-age main sequence (ZAMS) with solar metallicity (Z = 0.019) and with Z = 0.001 by the same authors are also shown with a dashed and a dotted line, respectively. The lithium-rich giant candidates listed in Table 4 are enclosed in open squares. The two giants with the highest Li abundance are labeled as in Table 3.