We report novel observational evidence on the evolutionary status of lithium-rich giant stars by combining asteroseismic and lithium abundance data. Comparing observations and models of the asteroseismic gravity-mode period spacing ΔΠ₁, we find that super-Li-rich giants (SLRs, A(Li)>3.2 dex) are almost exclusively young red-clump (RC) stars. Depending on the exact phase of evolution, which requires more data to refine, SLR stars are either (i) less than ∼2Myr or (ii) less than ∼40Myr past the main core helium flash (CHeF). Our observations set a strong upper limit for the time of the inferred Li-enrichment phase of <40 Myr post-CHeF, lending support to the idea that lithium is produced around the time of the CHeF. In contrast, the more evolved RC stars (>40 Myr post-CHeF) generally have low lithium abundances (A(Li) <1.0 dex). Between the young, super-Li-rich phase, and the mostly old, Li-poor RC phase, there is an average reduction of lithium by about 3 orders of magnitude. This Li destruction may occur rapidly. We find the situation to be less clear with stars having Li abundances between the two extremes of super-Li-rich and Li-poor. This group, the “Li-rich” stars (3.2 > A(Li)> 1.0 dex), shows a wide range of evolutionary states.

我们通过结合星震和锂丰度数据报告了有关富锂巨星演化状态的新观测证据。比较星震重力模式周期间隔ΔΠ _{1 的}观测和模型，我们发现超富锂巨星（SLRs，A(Li)>3.2 dex) 几乎完全是年轻的红团 (RC) 星。根据演化的确切阶段，需要更多数据来完善，SLR 恒星要么（i）小于~2Myr，要么（ii）在主核心氦闪（CHeF）之后小于~40Myr。我们的观察为推断的锂富集阶段的时间设定了一个很强的上限，即<40 Myr 后 CHeF，支持锂在 CHeF 前后生产的想法。相比之下，进化程度更高的 RC 星（>40 Myr 后 CHeF）通常锂丰度较低（A(Li) <1.0 dex)。在年轻的超级富锂相和大多数年老的贫锂 RC 相之间，锂平均减少了大约 3 个数量级。这种锂破坏可能会迅速发生。我们发现，当恒星的锂丰度介于超级富锂和贫锂这两个极端之间时，情况就不太清楚了。这组“富锂”恒星（3.2 > A (Li)> 1.0 dex）显示出广泛的演化状态。