THE LI/LI-6 RATIO AND THE STELLAR YIELD OF LI-7

The detection of the lithium isotopic ratio in the present galactic gas by Lemoine et al. (1992) can be related to the flux of galactic cosmic rays, to give information on the stellar source of Li-7. We obtain the following average yield for the last 4.5 Gyr in the solar neighborhood: 20 M. of Li-7 per gigayear per 10(10) M. of gas, corresponding to an addition of DELTA (Li-7/H) quite comparable to the difference between the Population I and Population II abundances. This observation is of relevance for the estimation of the Big-Bang yield of lithium, alleviating the need of primordial values as high as Population I stars (which would have been later depleted by surface processes in Population II stars).