FLARE PRODUCTION OF LI-6 IN POPULATION II-STARS

Motivated by the recent report of a Li-6 detection in the atmosphere of HD 84937, we couple stellar evolution calculations with light-isotope production via stellar flares. We find that as a consequence of their small convective envelope mass near the turnoff point, low-metallicity dwarfs and subgiants may possess observable amounts of Li-6 arising from such flare activity. We point out an observational test which could discriminate between flare-produced Li-6 and protostellar Li-6. In the T-eff range 6000-6600 K, the Li-7/Li-6 ratio on the subgiant branch should increase as a function of T-eff if flare production is important, whereas the same ratio should be constant if a protostellar origin is the source of the observed lithium. The absence of a flare-produced variation in the Li-7/Li-6 ratio would allow for a more reliable inference of the-cosmologically important-atmospheric depletion mechanisms in stars.