The lack of lithium in older stars is apparently caused by the "mixing" of lithium into the interior of stars, where it is destroyed, while lithium is produced in younger stars.
Kurangnya litium pada bintang yang lebih tua rupanya disebabkan oleh "pencampuran" litium ke dalam interior bintang, di mana ia dihancurkan, sementara litium diproduksi di bintang yang lebih muda.