Lithium in an Extreme Halo Star

Echelle spectra show that BD +3°740 is an extreme Population II dwarf with a logarithmic metallicity [Fe/H] ≈ -2.9, a space velocity |v_LSR| ≈ 210 km s^-1, and an effective temperature T_e ≈ 6240K. Small corrections of the star's observed colors for interstellar reddening are derived from the observed interstellar D lines. The equivalent width W_λ = 17±3 mÅ of the Li I λ6707 line gives an abundance Li/H = (1.2±0.5)×10^-10, in agreement with previous results for two other extreme halo stars.