The vast majority of stars with mass similar to that of the Sun are expected to destroy lithium (Li) gradually over the course of their lives, via low-temperature nuclear burning. This has now been supported by observations of hundreds of thousands of red giant stars^1,2,3,4,5. Here we perform a large-scale systematic investigation into the Li content of stars in the red clump phase of evolution, which directly follows the red giant branch phase. Surprisingly, we find that all red clump stars have high levels of Li for their evolutionary stage, with an increase of a factor of 40 over the end of the red giant branch stage, on average. This suggests that all low-mass stars undergo an Li production phase between the tip of the red giant branch and the red clump. We demonstrate that our finding is not predicted by stellar theory, revealing a stark tension between observations and models. We also show that the well-studied^1,2,4,5,6 very Li-rich giants, with A(Li) > +1.5 dex, represent only the extreme tail of the Li enhancement distribution, comprising 3% of red clump stars. Our findings suggest a new definition limit for Li-richness in red clump stars, A(Li) > −0.9 dex, which is much lower than the limit of A(Li) > +1.5 dex used over many decades^1,5,6,7,8,9.

预期质量类似于太阳的绝大多数恒星将通过低温核燃烧在其生命过程中逐渐破坏锂（Li）。现在，通过观察成千上万的红色巨星^1,2,3,4,5支持了这一点。在这里，我们对红色丛状演化阶段中恒星的Li含量进行了大规模的系统研究，该阶段直接跟随红色巨星分支阶段。出乎意料的是，我们发现所有红色块状星在其进化阶段都具有较高水平的Li，与红色巨星分支阶段结束时相比平均增加了40倍。这表明所有低质量恒星都在红色巨星分支的顶端和红色丛之间经历了一次Li产生阶段。我们证明了我们的发现不是恒星理论所预测的，这揭示了观测与模型之间的强烈张力。我们还表明，经过精心研究的^1,2,4,5,6非常富锂的巨人，其中A（Li）> +1.5 dex，仅代表Li增强分布的最末端，包括3％的红色团星。我们的发现表明，新的红团星富锂定义极限为A（Li）> -0.9 dex，远低于数十年来使用的A（Li）> +1.5 dex的极限^{1,5,6 ，7,8,9}。