The chemical evolution of galaxies is governed by the chemical yields from stars, especially from Asymptotic Giant Branch (AGB) stars. This underlines the importance of understanding how AGB stars produce their elements by obtaining accurate stellar nucleosynthetic yields. Although AGB nucleosynthesis has general validity, critical uncertainties (such as the treatment of convective-driven mixing processes and mass loss) exist in current stellar models. Observations from post-Asymptotic Giant Branch (post-AGB) stars serve as excellent tools to quantify the strongest discrepancies, and eliminate crucial uncertainties that hamper stellar modelling. Our recent studies of post-AGB stars have shown an intriguing chemical diversity that ranges from stars that are extremely enriched in carbon and s -process elements to the discovery of the first post-AGB star with no traces of carbon nor s -process elements. Additionally, AGB nucleosynthesis is significantly affected by a binary companion. These results reflect the complexity that surrounds the element production in AGB stars. In this review, I will briefly present the intriguing chemical diversity observed in post-AGB stars and its implications on element/isotope production in AGB stars and stellar nucleosynthetic yields.

中文翻译：

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后 AGB 恒星作为宇宙元素起源的示踪剂

星系的化学演化受恒星的化学产率控制，尤其是渐近巨星分支 (AGB) 恒星。这强调了通过获得准确的恒星核合成产量来了解 AGB 恒星如何产生元素的重要性。尽管 AGB 核合成具有普遍的有效性，但当前的恒星模型中存在关键的不确定性（例如对流驱动的混合过程和质量损失的处理）。后渐近巨星分支（post-AGB）恒星的观测是量化最强差异的绝佳工具，并消除了阻碍恒星建模的关键不确定性。我们最近对后 AGB 恒星的研究显示了一种有趣的化学多样性，从富含碳和 s 过程元素的恒星到发现第一颗没有碳和 s 过程元素痕迹的后 AGB 恒星。此外，AGB 核合成受到二元伴体的显着影响。这些结果反映了围绕 AGB 恒星元素产生的复杂性。在这篇综述中，我将简要介绍在后 AGB 恒星中观察到的有趣的化学多样性及其对 AGB 恒星中元素/同位素产生和恒星核合成产率的影响。