DETECTION OF THE LI-I LAMBDA-6104 TRANSITION IN THE POPULATION-II STAR HD-140283

Lithium is one of the few primordially produced elements. The value of the primordial Li is taken to be that observed in metal-poor dwarfs, where it is not contaminated by stellar Li sources that act on longer timescales. The atmospheric abundance is currently derived from the Li I lambda 6707 resonance transition, and the validity of the models em ployed has been questioned (Kurucz). In this Letter, we report the fir st detection of the Li I lambda 6104 2 P-2-3 D-2 subordinate transitio n in the prototype Population II star HD 140283. The same Li abundance of (Li/H) = 1.4 x 10(-10) is found to be consistent with both the res onance and subordinate lines. The two lines form at different depths i n the atmosphere, implying that the one-dimensional, homogeneous atmos pheric models used in the abundance determination are essentially corr ect. When coupled with the standard big bang yields, the Li in the hal o dwarfs provides two solutions for the baryon-to-photon ratio eta(10) = n(b)/n(gamma) x 10(10) and for the present baryon density Omega(b)h (70)(2) = 0.0748 eta(10): a first solution at eta(10) approximate to 1 .8, which is consistent with the eta(10) implied by the high deuterium values D/H approximate to 2 x 10(-4) observed in some quasar absorpti on systems (Webb et al.); and a second solution at eta(10) approximate to 4, which is consistent, within the errors, with the low deuterium D/H = 3.4 x 10(-5) measured in other quasar absorption systems (Burles & Tytler).